JP2022156849A - Fibrous cellulose-containing substance, fibrous cellulose composite fiber, and method for producing fibrous cellulose-containing substance - Google Patents

Abstract

To provide a fibrous cellulose-containing substance which is excellent in dispersibility even when dried and a method for producing the same, and a fibrous cellulose composite resin which is excellent in strength.SOLUTION: A fibrous cellulose-containing substance is provided which is added to a resin, wherein the fibrous cellulose has an average fiber width of 0.1-19 μm, has a hydroxyl group substituted with a carbamate group, and includes powder interacting with the fibrous cellulose. A fibrous cellulose composite resin is provided which uses the fibrous cellulose-containing substance as a fibrous cellulose. A method for producing a fibrous cellulose-containing substance is provided in which a fibrous cellulose having a hydroxyl group substituted with a carbamate group is dissociated in such a manner that the fibrous cellulose has an average fiber width of 0.1-19 μm, and the dissociated fibrous cellulose is mixed with powder interacting with the fibrous cellulose, thereby obtaining a mixed liquid, the mixed liquid is dried.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a fibrous cellulose-containing material, a fibrous cellulose composite resin, and a method for producing a fibrous cellulose-containing material.

In recent years, the use of fine fibers such as cellulose nanofibers and microfiber cellulose (microfibrillated cellulose) as reinforcing materials for resins has attracted attention. However, since the fine fibers are hydrophilic and the resin is hydrophobic, there is a problem in the dispersibility of the fine fibers when using the fine fibers as a reinforcing material for the resin. Accordingly, the present inventors proposed substituting the hydroxy groups of fine fibers with carbamate groups (see Patent Document 1). According to this proposal, the dispersibility of the fine fibers is improved, thereby improving the reinforcing effect of the resin. However, fine fibers aggregate during drying, but since this aggregation is strong, there is a problem in terms of dispersibility when using dried fine fibers as a reinforcing material for resins.

JP 2019-1876 A

The main problem to be solved by the present invention is to provide a fibrous cellulose-containing material that is excellent in dispersibility even when dried, a method for producing the same, and a fibrous cellulose composite resin that is excellent in strength.

In the conventional development, for example, the development of the above-mentioned patent document, the focus is placed on the dispersibility of fine fibers when they are held in a dispersion state, and esterification, etherification, amidation, sulfidation, etc. , found that the introduction of carbamate (carbamation) is superior among many modification methods. In contrast, the present invention focuses on the dispersibility of fine fibers when the fine fibers are once dried and then mixed with a resin. The inventors have found that the above-mentioned problems can be solved by pursuing other substances and physical properties to be used together with them, and have arrived at the idea. The means conceived in this way are as follows.

(Means according to claim 1)
A fibrous cellulose inclusion added to the resin,
The fibrous cellulose has an average fiber width of 0.1 to 19 μm, and some or all of the hydroxyl groups are substituted with carbamate groups,
comprising a powder that interacts with the fibrous cellulose;
A fibrous cellulose-containing material characterized by:

(Means according to claim 2)
The interacting powder has a 90% particle size/10% particle size of 2 to 1000.
The fibrous cellulose inclusion according to claim 1.

(Means according to claim 3)
The volume average particle diameter of the interacting powder is 0.01 to 10000 μm, and the volume average particle diameter (μm) of the interacting powder/average fiber length (μm) of the fibrous cellulose is 0.005 to 5000. is
The fibrous cellulose containing material according to claim 1 or claim 2.

(Means according to claim 4)
The fibrous cellulose has a fiber length of less than 0.2 mm in a proportion of 5% or more and a fiber length of 0.2 to 0.6 mm in a proportion of 10% or more.
The fibrous cellulose-containing material according to any one of claims 1-3.

(Means according to claim 5)
The fibrous cellulose has an average fiber length of 1.0 mm or less, an average fiber width of 10 μm or less, and a fibrillation rate of 2.5% or more.
The fibrous cellulose-containing material according to any one of claims 1-4.

(Means according to claim 6)
The interacting powder is an acid-modified resin having an acid value of 2.0% or more,
The fibrous cellulose-containing material according to any one of claims 1-5.

(Means according to claim 7)
wherein said interacting powder is maleic anhydride modified polypropylene;
The fibrous cellulose-containing material according to any one of claims 1-6.

(Means according to claim 8)
A fibrous cellulose composite resin in which fibrous cellulose and resin are mixed,
The fibrous cellulose-containing material according to any one of claims 1 to 7 is used as the fibrous cellulose,
A fibrous cellulose composite resin characterized by:

(Means according to claim 9)
Fibrous cellulose in which some or all of the hydroxyl groups have been substituted with carbamate groups is defibrated so that the average fiber width is 0.1 to 19 μm, and mixed with the powder that interacts with the fibrous cellulose to obtain a mixed solution. get
drying the mixture,
A method for producing a fibrous cellulose-containing material, characterized by:

INDUSTRIAL APPLICABILITY According to the present invention, a fibrous cellulose-containing material excellent in dispersibility even when dried, a method for producing the same, and a fibrous cellulose composite resin excellent in strength are provided.

Next, a mode for carrying out the invention will be described. Note that this embodiment is an example of the present invention. The scope of the present invention is not limited to the scope of this embodiment.

The fibrous cellulose-containing material of the present embodiment is added to a resin, and the fibrous cellulose (hereinafter also referred to as "cellulose fiber") has an average fiber width of 0.1 to 19 μm and a hydroxyl group (—OH groups) are partially or entirely substituted with carbamate groups. In addition, the fibrous cellulose-containing material contains powder that interacts with fibrous cellulose (hereinafter also simply referred to as "interacting powder"). The powder is preferably an acid-modified resin whose acid groups ionically bond with some or all of the carbamate groups. Moreover, a fibrous cellulose composite resin is obtained by adding this fibrous cellulose-containing material to a resin. Furthermore, in the method for producing a fibrous cellulose-containing material, fibrous cellulose in which some or all of the hydroxyl groups have been substituted with carbamate groups is defibrated so that the average fiber width is 0.1 to 19 μm, and the fibers are A powder that interacts with the cellulose is added to obtain a mixed liquid, and the mixed liquid is dried. A detailed description will be given below.

(fibrous cellulose)
The fibrous cellulose, which is fine fibers in this embodiment, is microfiber cellulose (microfibrillated cellulose) having an average fiber diameter of 0.1 to 19 μm. Microfiber cellulose significantly improves the reinforcing effect of the resin. Microfiber cellulose is also easier to modify with carbamate groups (carbamate) than cellulose nanofibers, which are also fine fibers. However, it is more preferred to carbamate the cellulosic feedstock prior to micronization, in which case microfiber cellulose and cellulose nanofibers are equivalent.

In this embodiment, microfiber cellulose means fibers having a larger average fiber width than cellulose nanofibers. Specifically, the average fiber diameter (width) is, for example, 0.1 to 19 μm, preferably 0.2 to 10 μm, more preferably over 0.5 to 10 μm. If the average fiber diameter of the fibrous cellulose is less than 0.1 μm (below), it is no different from cellulose nanofibers, and there is a risk that the effect of improving the strength (especially bending elastic modulus) of the resin cannot be sufficiently obtained. . In addition, defibration takes a long time, and a large amount of energy is required. Furthermore, the dewaterability of the cellulose fiber slurry deteriorates. When the dehydration property deteriorates, a large amount of energy is required for drying, and if a large amount of energy is applied to drying, the fibrous cellulose may be thermally degraded, resulting in a decrease in strength. In addition, when defibration is performed to an average fiber diameter of less than 0.1 μm, the variation in the fiber length of the fibrous cellulose becomes small, making it difficult to exhibit the effects of the present embodiment that define the particle size distribution of the interacting powder. .

On the other hand, if the average fiber diameter of the fibrous cellulose exceeds (exceeds) 19 μm, it is no different from that of pulp, and the reinforcing effect may not be sufficient. In addition, when the average fiber diameter exceeds 19 μm, the variation in fiber length of the fibrous cellulose is small, and the effect of the present embodiment that defines the particle size distribution of the interacting powder is difficult to exhibit. In addition, when the average fiber diameter is 10 μm or less, the average fiber length is 1.0 mm or less and the fibrillation ratio is 2.5% or more.

The mode diameter (width) of fibrous cellulose is preferably 0.1 to 19 μm, more preferably 0.5 to 10 μm, particularly preferably 1 to 6 μm. In this regard, in the present embodiment in which the fiber length of the fibrous cellulose varies as described later, fibers with a large fiber width are mixed in a certain proportion during defibration, so the fibrous cellulose is specified by the average fiber diameter. It is preferable to specify the mode diameter with the largest number. From this point of view, if the mode diameter is less than 0.1 μm, the proportion of cellulose nanofibers tends to increase, and the cellulose nanofibers aggregate with each other, possibly resulting in an insufficient reinforcing effect. On the other hand, if the mode diameter exceeds 19 μm, the ratio of pulp tends to increase, and it can be said that the reinforcing effect may not be sufficient.

The method for measuring the average fiber diameter of fine fibers (microfiber cellulose and cellulose nanofiber) is as follows.
First, 100 ml of an aqueous dispersion of fine fibers having a solid concentration of 0.01 to 0.1% by mass is filtered through a Teflon (registered trademark) membrane filter, and the solvent is replaced once with 100 ml of ethanol and 3 times with 20 ml of t-butanol. do. It is then freeze-dried and coated with osmium to form a sample. This sample is observed with an electron microscope SEM image at a magnification of 3,000 times to 30,000 times depending on the width of the constituent fibers. Specifically, two diagonal lines are drawn on the observation image, and three straight lines passing through the intersections of the diagonal lines are arbitrarily drawn. Furthermore, the width of a total of 100 fibers intersecting with these three straight lines is visually measured. Then, the median diameter of the measured value is taken as the average fiber diameter.

In addition, the mode diameter of fine fibers is measured by a fiber analyzer "FS5" manufactured by Valmet.

By the way, when the fibrous cellulose is microfibrous cellulose, it has a characteristic that the variation in fiber length and the like increases. This is for the following reasons.
First, pulp is produced, for example, by boiling chips with alkali under pressure and then loosening them when the pressure returns to normal, without mechanical fibrillation. Therefore, wood cells are isolated as they are to form a pulp, and the fiber length and the like are relatively uniform. In addition, the cellulose nanofibers consist of fibers with independent fluffing portions, and the fluffing portions of the cellulose microfibers are separated independently. Therefore, the fiber length and the like are relatively uniform. On the other hand, the microfiber cellulose is in a stage where the fibers are fluffing due to the application of a mechanical defibration force to the pulp, and therefore the distribution of the fiber length and the like is widened.

Microfiber cellulose usually has a fiber length of less than 0.2 mm in a proportion of 5% or more and a fiber length of 0.2 to 0.6 mm in a proportion of 10% or more, preferably a fiber length of less than 0.2 mm. 8% or more, a fiber length of 0.2 to 0.6 mm is 13% or more, more preferably a fiber length of less than 0.2 mm is 20% or more, and a fiber length is 0.2 to 0.2 mm. A ratio of 6 mm is 16% or more. When the fiber length of the microfiber cellulose is varied as described above, the action and effect of the present embodiment that regulates the particle size distribution of the interacting powder are exhibited fully.

In the above, if the proportion of fibers having a fiber length of less than 0.2 mm is too large, the entanglement with interacting powder having a large particle size becomes insufficient, which may lead to a decrease in dispersibility. On the other hand, if the proportion of fibers having a length of more than 0.6 mm is too high, the entanglement with the interacting powder of small particle size becomes insufficient, which may lead to a decrease in dispersibility.

As described above, the variation in the fiber length, etc. of microfiber cellulose is relatively large. Then, there is a possibility that the reinforcing effect of the resin as the fiber itself is inferior. Therefore, the proportion of fibrous cellulose having a fiber length of 0.2 to 0.6 mm is preferably 10 to 90%, more preferably 14 to 70%, and particularly preferably 16 to 50%. If the proportion of fibers having a length of 0.2 to 0.6 mm is less than 14%, the entanglement with the interacting powder will be insufficient, and as a result, there is a possibility that the reinforcing effect will not be exhibited sufficiently.

Microfiber cellulose can be obtained by defibrating (refining) a cellulose raw material (hereinafter also referred to as "raw material pulp"). Raw material pulp includes, for example, wood pulp made from broad-leaved trees, coniferous trees, etc., non-wood pulp made from straw, bagasse, cotton, hemp, pistil fibers, etc., and waste paper pulp made from recovered waste paper, waste paper, etc. (DIP) or the like can be selected and used. The various raw materials described above may be, for example, in the form of pulverized (powdered) material such as cellulose powder.

However, in order to avoid contamination with impurities as much as possible, it is preferable to use wood pulp as the raw material pulp. As the wood pulp, for example, one or more of chemical pulps such as hardwood kraft pulp (LKP) and softwood kraft pulp (NKP), mechanical pulp (TMP), etc. can be selected and used.

The hardwood kraft pulp may be bleached hardwood kraft pulp, unbleached hardwood kraft pulp, or semi-bleached hardwood kraft pulp. Similarly, the softwood kraft pulp may be softwood bleached kraft pulp, softwood unbleached kraft pulp, or softwood semi-bleached kraft pulp.

Examples of mechanical pulp include stone ground pulp (SGP), pressure stone ground pulp (PGW), refiner ground pulp (RGP), chemi ground pulp (CGP), thermo ground pulp (TGP), ground pulp (GP), One or more of thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), refiner mechanical pulp (RMP), bleached thermomechanical pulp (BTMP) and the like can be selected and used.

The raw pulp can be pretreated by chemical means prior to defibration. Examples of chemical pretreatments include hydrolysis of polysaccharides with acid (acid treatment), hydrolysis of polysaccharides with enzymes (enzyme treatment), swelling of polysaccharides with alkali (alkali treatment), and oxidation of polysaccharides with an oxidizing agent ( oxidation treatment), reduction of polysaccharides with a reducing agent (reduction treatment), and the like. However, as the chemical pretreatment, it is preferable to perform enzyme treatment, and in addition, it is more preferable to perform one or more treatments selected from acid treatment, alkali treatment, and oxidation treatment. The enzymatic treatment will be described in detail below.

At least one of a cellulase enzyme and a hemicellulase enzyme is preferably used as the enzyme used for the enzymatic treatment, and it is more preferable to use both together. The use of these enzymes makes the fibrillation of cellulosic raw materials easier. Cellulase enzymes cause decomposition of cellulose in the presence of water. In addition, hemicellulase enzymes cause decomposition of hemicellulose in the presence of water.

Cellulase enzymes include, for example, Trichoderma genus, Acremonium genus, Aspergillus genus, Phanerochaete genus, Trametes genus genus Humicola, genus Bacillus, genus Schizophyllum, genus Streptomyces, genus Pseudomonas, etc. Enzymes can be used. These cellulase enzymes can be purchased as reagents or commercial products. Commercially available products include, for example, cellulucine T2 (manufactured by HPI), Meicerase (manufactured by Meiji Seika Co., Ltd.), Novozym 188 (manufactured by Novozym), Multifect CX10L (manufactured by Genencore), cellulase enzyme GC220 (manufactured by Genencore). ) etc. can be exemplified.

Both EG (endoglucanase) and CBH (cellobiohydrolase) can be used as cellulase enzymes. EG and CBH may be used alone or in combination. It may also be used in combination with a hemicellulase enzyme.

Examples of hemicellulase enzymes that can be used include xylanase, an enzyme that degrades xylan, mannase, an enzyme that degrades mannan, and arabanase, an enzyme that degrades araban. can. Pectinase, which is an enzyme that degrades pectin, can also be used.

Hemicellulose is a polysaccharide excluding pectins present between cellulose microfibrils in plant cell walls. Hemicelluloses are very diverse and differ between wood types and cell wall layers. Glucomannan is the main component in the secondary walls of coniferous trees, and 4-O-methylglucuronoxylan is the main component in the secondary walls of hardwoods. Therefore, when obtaining fine fibers from softwood bleached kraft pulp (NBKP), it is preferable to use mannase. In addition, when obtaining fine fibers from hardwood bleached kraft pulp (LBKP), it is preferable to use xylanase.

The amount of enzyme added to the cellulose raw material is determined, for example, by the type of enzyme, the type of wood used as the raw material (coniferous or hardwood), the type of mechanical pulp, and the like. However, the amount of enzyme added to the cellulose raw material is preferably 0.1 to 3% by mass, more preferably 0.3 to 2.5% by mass, and particularly preferably 0.5 to 2% by mass. If the added amount of the enzyme is less than 0.1% by mass, there is a possibility that the effect of the addition of the enzyme cannot be sufficiently obtained. On the other hand, if the added amount of the enzyme exceeds 3% by mass, cellulose may be saccharified and the yield of fine fibers may decrease. Moreover, there is also a problem that an improvement in the effect commensurate with an increase in the amount added cannot be recognized.

When a cellulase enzyme is used as the enzyme, the pH during the enzyme treatment is preferably in the weakly acidic range (pH=3.0 to 6.9) from the viewpoint of the reactivity of the enzyme reaction. On the other hand, when a hemicellulase enzyme is used as the enzyme, the pH during the enzyme treatment is preferably in the weakly alkaline range (pH=7.1 to 10.0).

The temperature during enzyme treatment is preferably 30 to 70°C, more preferably 35 to 65°C, and particularly preferably 40 to 60°C, regardless of whether a cellulase enzyme or a hemicellulase enzyme is used as the enzyme. . If the temperature during the enzyme treatment is 30° C. or higher, the enzyme activity is less likely to decrease and the treatment time can be prevented from becoming longer. On the other hand, if the temperature during the enzyme treatment is 70° C. or lower, deactivation of the enzyme can be prevented.

The enzymatic treatment time is determined by, for example, the type of enzyme, the temperature of the enzymatic treatment, the pH at the time of the enzymatic treatment, and the like. However, the general enzymatic treatment time is 0.5 to 24 hours.

After enzymatic treatment, the enzyme is preferably deactivated. Methods for inactivating the enzyme include, for example, a method of adding an alkaline aqueous solution (preferably pH 10 or higher, more preferably pH 11 or higher), a method of adding hot water at 80 to 100°C, and the like.

Next, the method of alkali treatment will be described.
Alkaline treatment prior to fibrillation dissociates some of the hydroxyl groups of hemicellulose and cellulose in the pulp, anionizing the molecules, weakening intramolecular and intermolecular hydrogen bonds, and promoting the dispersion of cellulose raw materials during fibrillation. be.

Alkali used for alkali treatment include, for example, sodium hydroxide, lithium hydroxide, potassium hydroxide, aqueous ammonia solution, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, and the like. An organic alkali or the like can be used. However, from the viewpoint of production cost, it is preferable to use sodium hydroxide.

If enzymatic treatment, acid treatment, or oxidation treatment is performed prior to defibration, the water retention of the microfiber cellulose can be lowered, the crystallinity can be increased, and the homogeneity can be enhanced. In this regard, when the water retention of the microfiber cellulose is low, it becomes easy to dewater, and the dewaterability of the cellulose fiber slurry is improved.

When the raw material pulp is subjected to enzyme treatment, acid treatment, or oxidation treatment, the hemicellulose and amorphous regions of cellulose in the pulp are decomposed. As a result, the defibration energy can be reduced, and the uniformity and dispersibility of the cellulose fibers can be improved. However, since pretreatment reduces the aspect ratio of the microfiber cellulose, it is preferable to avoid excessive pretreatment when used as a reinforcing material for resins.

For defibration of raw material pulp, for example, beaters, high-pressure homogenizers, homogenizers such as high-pressure homogenizers, grinders, stone mills such as grinders, single-screw kneaders, multi-screw kneaders, kneader refiners, jet mills, etc. It can be carried out by beating the raw material pulp using However, it is preferable to use a refiner or a jet mill.

The average fiber length (average length of single fibers) of the microfiber cellulose is preferably 0.10 to 2.00 mm, more preferably 0.12 to 1.50 mm, and particularly preferably 0.15 to 1.00 mm. be. If the average fiber length is less than 0.10 mm, a three-dimensional network cannot be formed between the fibers, and there is a risk that the reinforcing effect (especially the flexural modulus) of the composite resin will decrease. It may also not entangle well with interacting powders. On the other hand, if the average fiber length exceeds 2.00 mm, there is a risk that the reinforcing effect will be insufficient because the fiber length is the same as that of raw material pulp. Also, the fibers can clump together and not be sufficiently entangled with the interacting powder.

The average fiber length of the cellulose raw material, which is the raw material of the microfiber cellulose, is preferably 0.50 to 5.00 mm, more preferably 1.00 to 3.00 mm, and particularly preferably 1.50 to 2.50 mm. If the average fiber length of the cellulose raw material is less than 0.50 mm, the reinforcing effect of the resin may not be sufficiently obtained during defibration treatment. On the other hand, if the average fiber length exceeds 5.00 mm, it may be disadvantageous in terms of production cost during fibrillation.

The average fiber length of microfiber cellulose can be arbitrarily adjusted by, for example, selection of raw material pulp, pretreatment, defibration, and the like.

The aspect ratio of the microfiber cellulose is preferably 2-15,000, more preferably 10-10,000. If the aspect ratio is less than 2, a three-dimensional network cannot be constructed, so even if the average fiber length exceeds 0.10 mm, the reinforcing effect may be insufficient. In addition, if the aspect ratio is less than 2, the number of points that can interact with the interacting powder having a sphere-like shape is too small. can not be sufficiently exhibited, and the reinforcing effect may be insufficient. On the other hand, if the aspect ratio exceeds 15,000, there is a risk that the cellulose microfibers will be entangled with each other, resulting in insufficient dispersion in the resin. In addition, there is a possibility that the fibers interact with each other and the interaction with the interacting powder does not occur sufficiently, resulting in an insufficient reinforcing effect.

The aspect ratio is the value obtained by dividing the average fiber length by the average fiber width. As the aspect ratio increases, the number of locations where catching occurs increases, so that the reinforcing effect increases.

The fibrillation rate of the microfiber cellulose is preferably 1.0-30.0%, more preferably 1.5-20.0%, particularly preferably 2.5-15.0%. If the fibrillation rate exceeds 30.0%, the contact area with water becomes too large, so even if defibration is performed in a range in which the average fiber width remains at 0.1 μm or more, dehydration may become difficult. be. On the other hand, if the fibrillation rate exceeds 30.0%, the surface area becomes too large and the fibers tend to retain water, which may make it difficult to interact with the interacting powder. On the other hand, if the fibrillation rate is less than 1.0%, hydrogen bonding between fibrils is reduced, and a strong three-dimensional network may not be formed. Also, if the fibrillation rate is less than 2.5%, there is a tendency for poor clinging to interacting powders.

The fiber length and fibrillation rate of the fiber are measured with a fiber analyzer "FS5" manufactured by Valmet.

The crystallinity of the microfibrous cellulose is preferably 50% or higher, more preferably 55% or higher, particularly preferably 60% or higher. When the degree of crystallinity is less than 50%, although the miscibility with other cellulose fibers such as pulp and cellulose nanofibers is improved, the strength of the fibers themselves is lowered, so the strength of the resin cannot be improved. There is a risk. On the other hand, the crystallinity of the microfibrous cellulose is preferably 95% or less, more preferably 90% or less, particularly preferably 85% or less. If the degree of crystallinity exceeds 95%, the ratio of strong hydrogen bonds in the molecule increases, the fiber itself becomes rigid, and the dispersibility deteriorates.

The crystallinity of microfiber cellulose can be arbitrarily adjusted by, for example, selection of raw material pulp, pretreatment, and refining treatment.

Crystallinity is a value measured according to JIS K 0131 (1996).

The pulp viscosity of the microfiber cellulose is preferably 2 cps or greater, more preferably 4 cps or greater. If the pulp viscosity of the microfiber cellulose is less than 2 cps, it may be difficult to suppress the aggregation of the microfiber cellulose. Further, if the pulp viscosity is less than 2 cps, the reinforcing properties of the resin may be insufficient even if the interaction with the interacting powder is exhibited.

Pulp viscosity is a value measured according to TAPPI T230.

The freeness of the microfibrous cellulose is preferably 500 ml or less, more preferably 300 ml or less, particularly preferably 100 ml or less. If the freeness of the microfiber cellulose exceeds 500 ml, the effect of improving the strength of the resin may not be obtained sufficiently. In addition, the entanglement with the interacting powder becomes poor, and there is a possibility that the agglomeration of the fibers cannot be sufficiently suppressed.

Freeness is a value measured according to JIS P8121-2 (2012).

The zeta potential of the microfiber cellulose is preferably −150 to 20 mV, more preferably −100 to 0 mV, particularly preferably −80 to −10 mV. If the zeta potential is less than -150 mV, the compatibility with the resin may be significantly reduced and the reinforcing effect may be insufficient. On the other hand, when the zeta potential exceeds 20 mV, the dispersion stability may deteriorate.

The water retention of the microfibrous cellulose is preferably 80-400%, more preferably 90-350%, particularly preferably 100-300%. If the water retention is less than 80%, the reinforcing effect may be insufficient because it is the same as the raw material pulp. On the other hand, if the water retention exceeds 400%, the dewatering property tends to be poor and aggregation tends to occur. In this regard, the water retention of the microfiber cellulose can be lowered by substituting the hydroxy group of the fiber with a carbamate group, and the dehydration and drying properties can be improved.

The water retention of microfiber cellulose can be arbitrarily adjusted by, for example, selection of raw material pulp, pretreatment, defibration, and the like.

The degree of water retention is determined by JAPAN TAPPI No. 26 (2000).

The microfibrous cellulose of this form has carbamate groups. There is no particular limitation on how it is determined to have a carbamate group. For example, the cellulose raw material may be carbamate to have carbamate groups, or the microfiber cellulose (micronized cellulose raw material) may be carbamate to have carbamate groups. .

In addition, having a carbamate group means a state in which carbamate (ester of carbamic acid) is introduced into fibrous cellulose. A carbamate group is a group represented by --O--CO--NH--, for example, a group represented by --O--CO--NH ₂ , --O--CONHR, --O--CO--NR ₂ and the like. That is, the carbamate group can be represented by the following structural formula (1).

Here, each R is independently a saturated straight-chain hydrocarbon group, a saturated branched-chain hydrocarbon group, a saturated cyclic hydrocarbon group, an unsaturated straight-chain hydrocarbon group, an unsaturated branched-chain hydrocarbon group, It is at least one of an aromatic group and a derivative group thereof.

Examples of saturated linear hydrocarbon groups include linear alkyl groups having 1 to 10 carbon atoms such as methyl, ethyl and propyl groups.

Examples of saturated branched hydrocarbon groups include branched chain alkyl groups having 3 to 10 carbon atoms such as isopropyl group, sec-butyl group, isobutyl group and tert-butyl group.

Examples of saturated cyclic hydrocarbon groups include cycloalkyl groups such as cyclopentyl, cyclohexyl and norbornyl groups.

Examples of unsaturated linear hydrocarbon groups include linear alkenyl groups having 2 to 10 carbon atoms such as ethenyl, propen-1-yl, propen-3-yl, ethynyl, and propyne-1. -yl group, propyn-3-yl group and other linear alkynyl groups having 2 to 10 carbon atoms.

Examples of unsaturated branched hydrocarbon groups include branched chain alkenyl groups having 3 to 10 carbon atoms such as propen-2-yl group, buten-2-yl group and buten-3-yl group, butyne-3 A branched alkynyl group having 4 to 10 carbon atoms such as -yl group can be mentioned.

Examples of aromatic groups include phenyl group, tolyl group, xylyl group, naphthyl group and the like.

As the derivative group, the above saturated straight-chain hydrocarbon group, saturated branched-chain hydrocarbon group, saturated cyclic hydrocarbon group, unsaturated straight-chain hydrocarbon group, unsaturated branched-chain hydrocarbon group and aromatic group Groups in which one or more hydrogen atoms possessed are substituted with a substituent (eg, a hydroxy group, a carboxy group, a halogen atom, etc.) can be mentioned.

In microfibrous cellulose with carbamate groups (carbamate groups introduced), some or all of the more polar hydroxy groups are replaced with relatively less polar carbamate groups. Therefore, microfibrous cellulose with carbamate groups has low hydrophilicity and high affinity with low polar resins and the like. As a result, the microfiber cellulose having carbamate groups has excellent uniform dispersibility with the resin. Also, slurries of microfibrous cellulose with carbamate groups are less viscous and easier to handle.

The substitution ratio of carbamate groups to hydroxy groups of the microfiber cellulose is preferably 1.0 to 5.0 mmol/g, more preferably 1.2 to 3.0 mmol/g, particularly preferably 1.5 to 2.0 mmol/g. is g. When the substitution rate is 1.0 mmol/g or more, the effect of introducing carbamate, particularly the effect of improving the bending elongation of the resin, can be reliably exhibited. On the other hand, if the substitution rate exceeds 5.0 mmol/g, the cellulose fibers will not be able to maintain the shape of the fibers, and there is a risk that the reinforcing effect of the resin will not be obtained sufficiently.

The carbamate group substitution rate (mmol/g) refers to the amount of carbamate groups contained per 1 g of the cellulose raw material having carbamate groups. Cellulose is a polymer having anhydroglucose as a structural unit, and has three hydroxy groups per structural unit.

<Carbamate formation>
Regarding the point of introducing carbamate into microfiber cellulose (the cellulose raw material when carbamate conversion is performed before fibrillation; hereinafter the same applies, and may also be referred to as "microfiber cellulose, etc.") (carbamate conversion), as described above. There are a method in which a cellulose raw material is carbamate-ized and then pulverized, and a method in which a cellulose raw material is pulverized and then carbamate-ized. In this regard, in this specification, defibration of the cellulose raw material is described first, and then carbamate formation (modification) is described. However, defibration and carbamate can be performed either first. However, it is preferable to perform carbamate formation first and then defibrate. This is because the cellulose raw material before defibration has a high dehydration efficiency, and the cellulose raw material is easily defibrated by the heating accompanying carbamate formation.

The process of carbamating microfiber cellulose or the like can be divided primarily into, for example, a mixing process, a removal process, and a heat treatment. In addition, the mixing treatment and the removal treatment can be collectively referred to as an adjustment treatment for preparing a mixture to be subjected to heat treatment.

In the mixing process, microfiber cellulose or the like (as described above, it may be a cellulose raw material, hereinafter the same) and urea and / or a derivative of urea (hereinafter also simply referred to as "urea etc.") are mixed as a dispersion medium. Mix inside.

Examples of urea and urea derivatives include urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea, and compounds in which hydrogen atoms of urea are substituted with alkyl groups. can. These urea and urea derivatives can be used singly or in combination. However, it is preferred to use urea.

The lower limit of the mixing mass ratio of urea etc. to microfiber cellulose etc. (urea etc./microfiber cellulose etc.) is preferably 10/100, more preferably 20/100. On the other hand, the upper limit is preferably 300/100, more preferably 200/100. By setting the mixing mass ratio to 10/100 or more, the efficiency of carbamate formation is improved. On the other hand, even if the mixing mass ratio exceeds 300/100, carbamate formation plateaus.

The dispersion medium is usually water. However, other dispersion media such as alcohols and ethers, and mixtures of water and other dispersion media may also be used.

In the mixing process, for example, microfiber cellulose or the like and urea or the like are added to water, microfiber cellulose or the like is added to an aqueous solution of urea or the like, or urea or the like is added to a slurry containing microfiber cellulose or the like. may Moreover, in order to mix uniformly, you may stir after addition. Further, the dispersion containing microfiber cellulose or the like and urea or the like may contain other ingredients.

In the removal treatment, the dispersion medium is removed from the dispersion containing microfiber cellulose and the like and urea and the like obtained in the mixing treatment. By removing the dispersion medium, urea and the like can be efficiently reacted in the subsequent heat treatment.

The removal of the dispersion medium is preferably carried out by volatilizing the dispersion medium by heating. According to this method, only the dispersion medium can be efficiently removed while leaving components such as urea.

The lower limit of the heating temperature in the removal treatment is preferably 50°C, more preferably 70°C, and particularly preferably 90°C when the dispersion medium is water. By setting the heating temperature to 50° C. or higher, the dispersion medium can be efficiently volatilized (removed). On the other hand, the upper limit of the heating temperature is preferably 120°C, more preferably 100°C. If the heating temperature exceeds 120° C., the dispersion medium and urea may react with each other and urea may decompose alone.

The heating time in the removal treatment can be appropriately adjusted according to the solid content concentration of the dispersion. Specifically, it is, for example, 6 to 24 hours.

In the heat treatment following the removal treatment, a mixture of microfiber cellulose or the like and urea or the like is heat treated. In this heat treatment, some or all of the hydroxy groups of the microfiber cellulose or the like react with urea or the like and are substituted with carbamate groups. More specifically, when urea or the like is heated, it decomposes into isocyanic acid and ammonia as shown in the following reaction formula (1). Isocyanic acid is highly reactive and, for example, forms a carbamate group on the hydroxyl group of cellulose as shown in the following reaction formula (2).
NH ₂ -CO-NH ₂ →H-N=C=O + NH ₃ (1)
Cell-OH + H-N=C=O → Cell-O-CO-NH ₂ (2)
The lower limit of the heating temperature in the heat treatment is preferably 120°C, more preferably 130°C, particularly preferably the melting point of urea (about 134°C) or higher, still more preferably 140°C, most preferably 150°C. By setting the heating temperature to 120° C. or higher, carbamate formation is efficiently performed. The upper limit of the heating temperature is preferably 200°C, more preferably 180°C, and particularly preferably 170°C. If the heating temperature exceeds 200° C., the microfiber cellulose or the like may be decomposed and the reinforcing effect may be insufficient.

The lower limit of the heating time in the heat treatment is preferably 1 minute, more preferably 5 minutes, particularly preferably 30 minutes, still more preferably 1 hour, most preferably 2 hours. By setting the heating time to 1 minute or longer, the carbamate reaction can be reliably carried out. On the other hand, the upper limit of the heating time is preferably 15 hours, more preferably 10 hours. If the heating time exceeds 15 hours, it is not economical, and 15 hours is sufficient for carbamate formation.

Prolonged heating time, however, invites deterioration of the cellulose fibers. Therefore, the pH condition in the heat treatment becomes important. The pH is preferably pH 9 or higher, more preferably pH 9-13, and particularly preferably pH 10-12 under alkaline conditions. Also, as a second best measure, pH 7 or less, preferably pH 3 to 7, particularly preferably pH 4 to 7, acidic or neutral conditions. Under neutral conditions of pH 7 to 8, the average fiber length of the cellulose fibers may be shortened, and the reinforcing effect of the resin may be inferior. On the other hand, under alkaline conditions of pH 9 or higher, the reactivity of the cellulose fibers increases, the reaction with urea and the like is promoted, and the carbamate reaction proceeds efficiently. can be done. On the other hand, under acidic conditions of pH 7 or less, the reaction of decomposing urea and the like into isocyanic acid and ammonia proceeds, and the reaction to cellulose fibers is accelerated, resulting in an efficient carbamate reaction. can be secured to However, if possible, it is preferable to heat-treat under alkaline conditions. This is because acid hydrolysis of cellulose may proceed under acidic conditions.

The pH can be adjusted by adding an acidic compound (eg, acetic acid, citric acid, etc.) or an alkaline compound (eg, sodium hydroxide, calcium hydroxide, etc.) to the mixture.

As a device for heating in the heat treatment, for example, a hot air dryer, a paper machine, a dry pulp machine, or the like can be used.

The heat-treated mixture may be washed. This washing may be performed with water or the like. By this washing, unreacted and remaining urea and the like can be removed.

(slurry)
The microfiber cellulose is optionally dispersed in an aqueous medium to form a dispersion (slurry). It is particularly preferred that the entire amount of the aqueous medium is water, but it is also possible to use an aqueous medium that is partly another liquid that is compatible with water. Other liquids that can be used include lower alcohols having 3 or less carbon atoms.

The solid content concentration of the slurry is preferably 0.1-10.0% by mass, more preferably 0.5-5.0% by mass. If the solid content concentration is less than 0.1% by mass, excessive energy may be required during dehydration and drying. On the other hand, when the solid content concentration exceeds 10.0% by mass, the fluidity of the slurry itself is lowered, and when a dispersant is used, there is a possibility that uniform mixing may not be possible.

(interacting powders)
The fibrous cellulose inclusion of this form comprises a powder that interacts with fibrous cellulose. By including the interacting powder in the fibrous cellulose-containing material, the fibrous cellulose can be brought into a form capable of exhibiting the reinforcing properties of the resin. That is, when fibrous cellulose is used as a slurry, it is preferable to remove the aqueous medium contained in the slurry before compounding with the resin. However, when the aqueous medium is removed, the cellulose may irreversibly aggregate due to hydrogen bonding, making it impossible to sufficiently exhibit the reinforcing effect of the fiber. Therefore, by including powder that interacts with the fibrous cellulose slurry, hydrogen bonding between celluloses is physically inhibited. Further, in the case of non-interacting powders, there is a possibility that the non-interacting powders agglomerate during drying, but in the case of interacting powders, this possibility is low. From this point of view, the interacting powder is preferably an acid-modified resin, more preferably a maleic anhydride-modified resin, and particularly preferably a maleic anhydride-modified polypropylene (MAPP). Details of the acid-modified resin will be described later.

Here, to interact means to form a strong bond with cellulose by covalent bond, ionic bond, or metallic bond (that is, bonds by hydrogen bond and Van der Waals force are not included in the concept of interacting .). Preferably, a strong bond is a bond with a bond energy of 100 kJ/mol or more.

The volume average particle size of the interacting powder is preferably 0.01 to 10000 μm, more preferably 50 to 750 μm, particularly preferably 150 to 450 μm. If the volume average particle size exceeds 10,000 μm, the interacting powder may enter the gaps between the cellulose fibers and the effect of inhibiting aggregation may not be exhibited. On the other hand, when the volume average particle size is less than 0.01 μm, there is a possibility that hydrogen bonding between microfiber celluloses cannot be inhibited due to fineness.

The interacting powder preferably has a 90% particle size/10% particle size of 2-1000, more preferably 10-200. By setting the particle size ratio within this range, even when the fibrous cellulose is microfibrous cellulose and the fiber length varies, the effect of inhibiting the aggregation of interacting powders is fully exhibited. Specifically, when the 90% particle size/10% particle size ratio is less than 2, the particle sizes are too uniform, and it may be difficult to exhibit the effect of interaction only with fibers having a specific fiber length. On the other hand, if the ratio of 90% particle size/10% particle size is more than 1000, the variation in particle size becomes extremely large, possibly limiting the length of interacting fibers.

In the above, the 90% particle size means the particle size when the particle size is measured in order from the smallest particle size and the measured ratio is 90%. Moreover, the 10% particle size means the particle size when the measured ratio is 10% when the particle size is measured in ascending order.

The arithmetic standard deviation of the interacting powders is preferably 0.01-10000 μm, more preferably 1-5000 μm, particularly preferably 10-1000 μm. Even though the particle size of the powder varies as described above, there is a range of fibrous cellulose in the sense that the fibrous cellulose is microfibrous cellulose, thus specifying the arithmetic standard deviation of the powder. . In this regard, when the arithmetic standard deviation is less than 0.01 μm, the particle diameter becomes uniform, and it may be difficult to exhibit the effect of interaction only with fibers having a specific fiber length. On the other hand, if the arithmetic standard deviation exceeds 10,000 μm, the particle size becomes excessively non-uniform, the range of fiber lengths that can interact with each other widens, and it may be difficult to exhibit the effect of interaction.

Arithmetic standard deviation is a value measured by a particle size distribution analyzer (for example, a laser diffraction/scattering particle size distribution analyzer manufactured by Horiba, Ltd.).

The volume average particle diameter (μm) of interacting powder/average fiber length (μm) of fibrous cellulose is preferably 0.005 to 5000, more preferably 0.01 to 1000. Within this range, the powder and the fibers are more entangled, and aggregation of the fibers is suppressed. More specifically, when the volume average particle diameter of the interacting powder/average fiber length of the fibrous cellulose is less than 0.005, the fibers interact with each other and the interaction with the interacting powder is sufficient. However, the reinforcing effect may be insufficient. On the other hand, when the volume average particle diameter of the interacting powder/average fiber length of the fibrous cellulose exceeds 5000, the number of points that can interact with the interacting powder having a spherical shape becomes too small. There is a possibility that the reinforcing effect will be insufficient due to lack of interaction.

In this specification, the volume average particle size of the interacting powder is measured as it is or in the form of an aqueous dispersion using a particle size distribution analyzer (for example, a laser diffraction/scattering particle size distribution analyzer manufactured by Horiba, Ltd.). It is the volume average particle diameter calculated from the volume-based particle size distribution.

The interacting powder in this embodiment is preferably a resin powder. If the interacting powder is a resin powder, it melts during kneading and ceases to be grains, so the mixture of particles with different particle diameters has no effect at all. As the resin powder, for example, the same resin as used for obtaining the composite resin can be used. Of course, they may be of different types.

The content of the interacting powder is preferably 1 to 9,900% by mass, more preferably 5 to 1,900% by mass, particularly preferably 10 to 900% by mass, based on fibrous cellulose. If the blending amount is less than 1% by mass, it may enter the interstices of the cellulose fibers and the effect of suppressing aggregation may not be sufficiently exhibited. On the other hand, if the blending amount exceeds 9,900% by mass, there is a possibility that the function as cellulose fibers cannot be exhibited.

Inorganic powders can be used in addition to the interacting powders. When the interacting powder and the inorganic powder are used together, even when the inorganic powders and the interacting powders are mixed under the condition of agglomeration, the inorganic powder and the interacting powder are effectively prevented from cohesion. In addition, powder with a small particle size has a large surface area and is more susceptible to intermolecular forces than to gravity, and as a result, it tends to agglomerate. may not be loosened well in the slurry, or the powders may aggregate when the aqueous medium is removed, resulting in an insufficient effect of preventing the aggregation of the microfiber cellulose. However, it is believed that a combination of inorganic powders and interacting powders can mitigate self-agglomeration.

Examples of inorganic powders include simple substances and oxides of metal elements in Groups I to VIII of the periodic table, such as Fe, Na, K, Cu, Mg, Ca, Zn, Ba, Al, Ti, and silicon elements. , hydroxides, carbonates, sulfates, silicates, sulfites, and various clay minerals composed of these compounds. Specifically, for example, barium sulfate, calcium sulfate, magnesium sulfate, sodium sulfate, calcium sulfite, zinc oxide, ground calcium carbonate, ground calcium carbonate, aluminum borate, alumina, iron oxide, calcium titanate, aluminum hydroxide, Magnesium hydroxide, calcium hydroxide, sodium hydroxide, magnesium carbonate, calcium silicate, clay, wollastonite, glass beads, glass powder, silica gel, fumed silica, colloidal silica, silica sand, silica, quartz powder, diatomaceous earth, white carbon , glass fiber, and the like. A plurality of these inorganic powders may be contained. Further, it may be contained in waste paper pulp, or may be a so-called recycled filler obtained by recycling inorganic substances in papermaking sludge.

However, at least one inorganic powder selected from calcium carbonate, talc, white carbon, clay, calcined clay, titanium dioxide, aluminum hydroxide, recycled fillers, etc., which are suitably used as fillers and pigments for papermaking. is preferably used, more preferably at least one selected from calcium carbonate, talc and clay, and at least one of light calcium carbonate and heavy calcium carbonate is used Especially preferred. The use of calcium carbonate, talc, and clay facilitates formation of a composite with a matrix such as a resin. In addition, since it is a general-purpose inorganic material, there is an advantage that there are few restrictions on its use. Furthermore, calcium carbonate is particularly preferred for the following reasons. When using light calcium carbonate, it becomes easier to control the size and shape of the powder to be constant. Therefore, according to the size and shape of the cellulose fibers, the size and shape can be adjusted so that the effect of entering the gaps and suppressing the aggregation of the cellulose fibers can be easily generated, and the effect can be easily exerted with pinpoint accuracy. There is In addition, when heavy calcium carbonate is used, even if fibers of various sizes are present in the slurry, it will enter the gaps during the process of flocculating the fibers when the aqueous medium is removed, because the heavy calcium carbonate is amorphous. There is an advantage that it is possible to suppress aggregation of cellulose fibers with each other.

When the inorganic powder and the interacting powder are used together, the ratio of the average particle size of the inorganic powder to the average particle size of the interacting powder is preferably 1:0.1 to 1:10000, and 1:1 to 1:1000. is more preferred. Within this range, problems arising from the strength of its own cohesive force (for example, when mixing the powder and the microfiber cellulose slurry, the powder does not loosen well in the slurry, and when the aqueous medium is removed, the powder It is considered that the effect of preventing the aggregation of the microfiber cellulose can be fully exhibited without the problem of aggregation of the microfibers.

When inorganic powder and interacting powder are used in combination, the ratio of mass% of inorganic powder: mass% of interacting powder is preferably 1:0.01 to 1:100, and 1:0.1 to 1:10. is more preferred. It is considered that within this range, different types of powder can inhibit their own aggregation. Within this range, problems arising from the strength of its own cohesive force (for example, when mixing the powder and the microfiber cellulose slurry, the powder does not loosen well in the slurry, and when the aqueous medium is removed, the powder It is considered that the effect of preventing the aggregation of the microfiber cellulose can be fully exhibited without the problem of aggregation of the microfibers.

(Acid-modified resin)
As previously mentioned, the interacting powder is preferably a resin powder. Also, the resin is preferably an acid-modified resin. Acid-modified resins can ionically bond acid groups to some or all of the carbamate groups. Due to this ionic bond, the function of suppressing aggregation of the resin powder is effectively exhibited.

Examples of acid-modified resins that can be used include acid-modified polyolefin resins, acid-modified epoxy resins, acid-modified styrene elastomer resins, and the like. However, it is preferable to use an acid-modified polyolefin resin. An acid-modified polyolefin resin is a copolymer of an unsaturated carboxylic acid component and a polyolefin component.

As the polyolefin component, for example, one or more of alkene polymers such as ethylene, propylene, butadiene and isoprene can be selected and used. However, it is preferable to use polypropylene resin, which is a polymer of propylene.

As the unsaturated carboxylic acid component, for example, one or more selected from maleic anhydrides, phthalic anhydrides, itaconic anhydrides, citraconic anhydrides, citric anhydrides and the like can be used. Preferably, however, maleic anhydrides are used. In other words, it is particularly preferable to use a maleic anhydride-modified polypropylene resin.

The amount of the acid-modified resin to be mixed is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, and particularly preferably 10 to 200 parts by mass with respect to 100 parts by mass of the microfiber cellulose. Particularly when the acid-modified resin is a maleic anhydride-modified polypropylene resin, the amount is preferably 1 to 200 parts by mass, more preferably 10 to 100 parts by mass. If the mixed amount of the acid-modified resin is less than 0.1 parts by mass, the anti-agglomeration effect is not sufficient. On the other hand, if the mixing amount exceeds 1,000 parts by mass, the anti-agglomeration effect tends to decrease.

The weight average molecular weight of maleic anhydride-modified polypropylene is, for example, 1,000 to 100,000, preferably 3,000 to 50,000.

Moreover, the acid value of the maleic anhydride-modified polypropylene is preferably 0.5 mgKOH/g or more and 100 mgKOH/g or less, and more preferably 1 mgKOH/g or more and 50 mgKOH/g or less.

The acid value of the maleic anhydride-modified polypropylene is a value determined by titration with potassium hydroxide according to JIS-K2501.

(dispersant)
Microfibrous cellulose is more desirable when mixed with a dispersant. As the dispersing agent, a compound having an aromatic compound having an amine group and/or a hydroxyl group and an aliphatic compound having an amine group and/or a hydroxyl group are preferable.

Examples of compounds having an amine group and/or hydroxyl group in aromatics include anilines, toluidines, trimethylanilines, anisidines, tyramines, histamines, tryptamines, phenols, dibutylhydroxytoluenes, bisphenol A cresols, eugenols, gallic acids, guaiacols, picric acids, phenolphthaleins, serotonins, dopamines, adrenaline, noradrenaline, thymols, tyrosines, salicylic acids, methyl salicylates, anise alcohols , salicyl alcohols, sinapyl alcohols, diphenidols, diphenylmethanols, cinnamyl alcohols, scopolamines, tryptophors, vanillyl alcohols, 3-phenyl-1-propanols, phenethyl alcohols, phenoxyethanols , veratryl alcohols, benzyl alcohols, benzoins, mandelic acids, mandelonitriles, benzoic acids, phthalic acids, isophthalic acids, terephthalic acids, mellitic acids, and cinnamic acids.

Examples of compounds having an amine group and/or a hydroxyl group in an aliphatic group include capryl alcohols, 2-ethylhexanols, pelargon alcohols, capric alcohols, undecyl alcohols, lauryl alcohols, and tridecyl alcohols. , myristyl alcohols, pentadecyl alcohols, cetanols, stearyl alcohols, elaidyl alcohols, oleyl alcohols, linoleyl alcohols, methylamines, dimethylamines, trimethylamines, ethylamines, diethylamines, ethylenediamine triethanolamines, N,N-diisopropylethylamines, tetramethylethylenediamines, hexamethylenediamines, spermidines, spermines, amantadine, formic acids, acetic acids, propionic acids, butyric acids, valeric acids, Caproic acids, enanthic acids, caprylic acids, pelargonic acids, capric acids, lauric acids, myristic acids, palmitic acids, margaric acids, stearic acids, oleic acids, linoleic acids, linolenic acids, arachidonic acids, eicosapentaenoic acids, docosahexaenoic acids, sorbin acids and the like.

The above dispersants inhibit hydrogen bonding between cellulose fibers. Therefore, the microfiber cellulose is reliably dispersed in the resin when the microfiber cellulose and the resin are kneaded. The above dispersants also play a role in improving the compatibility of the microfiber cellulose and the resin. In this respect, the dispersibility of the microfiber cellulose in the resin is improved.

It is conceivable to add a compatibilizer (drug) separately when kneading the fibrous cellulose and the resin, but rather than adding the drug at this stage, the fibrous cellulose and the dispersant (drug) are mixed in advance. In this case, the drug is evenly attached to the fibrous cellulose, and the effect of improving the compatibility with the resin is enhanced.

Further, for example, polypropylene has a melting point of 160°C, and therefore fibrous cellulose and resin are kneaded at about 180°C. However, if the dispersing agent (liquid) is added in this state, it dries up in an instant. Therefore, there is a method of using a resin with a low melting point to prepare a masterbatch (composite resin with a high concentration of microfiber cellulose), and then lowering the concentration with a normal resin. However, resins with low melting points generally have low strength. Therefore, according to this method, the strength of the composite resin may decrease.

The amount of the dispersant mixed is preferably 0.1 to 1,000 parts by weight, more preferably 1 to 500 parts by weight, and particularly preferably 10 to 200 parts by weight, based on 100 parts by weight of the microfiber cellulose. If the amount of the dispersant mixed is less than 0.1 part by mass, there is a possibility that the improvement in resin strength will be insufficient. On the other hand, if the mixing amount exceeds 1,000 parts by mass, it becomes excessive and the resin strength tends to decrease.

In this regard, the above-mentioned acid-modified resin is intended to improve compatibility by forming an ionic bond between the acid group and the carbamate group of the microfiber cellulose, thereby enhancing the reinforcing effect. (Improved adhesion) and strength. On the other hand, the above-mentioned dispersant intervenes between the hydroxyl groups of the microfiber cellulose to prevent aggregation, thereby improving the dispersibility in the resin. , it can enter the narrow spaces between microfiber cellulose where the acid-modified resin cannot enter, and plays a role of improving dispersibility and strength. From the above viewpoints, the molecular weight of the acid-modified resin is preferably 2 to 2,000 times, preferably 5 to 1,000 times the molecular weight of the dispersant.

To explain the above in more detail, the interacting powder physically intervenes between the microfiber celluloses to inhibit hydrogen bonding, thereby improving the dispersibility of the microfiber cellulose. In particular, the acid-modified resin ionically bonds the acid groups with the carbamate groups of the microfiber cellulose. Therefore, it comes to be present around the fibers preferentially over other substances, and the effect of suppressing aggregation of the fibers is exhibited. Moreover, when the fibrous cellulose-containing material and the resin are mixed to form a composite resin, the composite resin plays a role of adhering the microfiber cellulose to the composite resin, thereby improving the mechanical strength of the composite resin. In this regard, the dispersing agent inhibits hydrogen bonding between microfiber celluloses, but since the interacting powder is micro-order, it physically intervenes to suppress hydrogen bonding. Therefore, although the dispersibility is lower than that of a dispersant, especially in the case of a resin powder, it melts itself and becomes a matrix, so it does not contribute to deterioration of physical properties. On the other hand, since the dispersant is at the molecular level and is extremely small, it is highly effective in preventing hydrogen bonding by covering the cellulose microfibers and improving the dispersibility of the cellulose microfibers. However, it may remain in the resin and work to reduce physical properties.

(Manufacturing method of composite resin)
Mixtures such as fibrous cellulose inclusions and dispersants can be dried and ground into a powder prior to kneading with the resin. According to this form, it is not necessary to dry the fibrous cellulose when kneading with the resin, and the heat efficiency is good. In addition, when the mixture contains an interacting powder or dispersant, even if the mixture is dried, there is a low possibility that the fibrous cellulose (microfiber cellulose) will not be redispersed.

The mixture is optionally dewatered to dehydrate prior to drying. For this dehydration, for example, one or more types are selected from dehydration devices such as belt presses, screw presses, filter presses, twin rolls, twin wire formers, valveless filters, center disk filters, membrane processing, and centrifugal separators. can be done using

Drying of the mixture includes, for example, rotary kiln drying, disk drying, air stream drying, medium fluidized drying, spray drying, drum drying, screw conveyor drying, paddle drying, uniaxial kneading drying, multi-screw kneading drying, vacuum drying, and stirring drying. It can be carried out by selecting and using one or more of these.

The dry mixture (dry matter) is ground to a powder. Pulverization of the dried product can be carried out by selecting and using one or more of, for example, bead mills, kneaders, dispersers, twist mills, cut mills, hammer mills, and the like.

The average particle size of the powder is preferably 1-10,000 μm, more preferably 10-5,000 μm, particularly preferably 100-1,000 μm. If the average particle size of the powder exceeds 10,000 μm, the kneadability with the resin may be poor. On the other hand, it is not economical because a large amount of energy is required to reduce the average particle size of the powder to less than 1 μm.

The average particle size of the powder can be controlled not only by controlling the degree of pulverization, but also by classification using a classifier such as a filter or cyclone.

The bulk specific gravity of the mixture (powder) is preferably 0.03 to 1.0, more preferably 0.04 to 0.9, and particularly preferably 0.05 to 0.8. A bulk specific gravity of more than 1.0 means that the hydrogen bonding between fibrous celluloses is stronger and it is not easy to disperse the fibrous cellulose in the resin. On the other hand, setting the bulk specific gravity below 0.03 is disadvantageous in terms of transportation costs.

Bulk specific gravity is a value measured according to JIS K7365.

The moisture content of the mixture (powder) is preferably 50% or less, more preferably 30% or less, and particularly preferably 10% or less. If the moisture content exceeds 50%, the energy required for kneading with the resin is enormous, which is not economical. The moisture content is a value calculated by the following formula, using a constant temperature drier, holding the sample at 105° C. for 6 hours or more, and using the mass after drying as the mass when no change in mass is observed.
Fiber moisture content (%) = [(mass before drying - mass after drying) / mass before drying] x 100

The powdery material (fibrous cellulose-containing material) obtained as described above is kneaded with a resin, if necessary, to obtain a fibrous cellulose composite resin. This kneading can be carried out, for example, by mixing a pellet-shaped resin and a powdery material, or by first melting the resin and then adding the powdery material to the melt. When resin powder such as acid-modified resin is used as the interacting powder, it can be kneaded immediately without being mixed with the resin to form a composite resin.

The mixture (powder, fibrous cellulose-containing material) preferably contains more than 55 parts by mass of fibrous cellulose, particularly 60 parts by mass or more, when the total amount is 100 parts by mass. Normally, when a mixture having a fibrous cellulose concentration exceeding 55 parts by mass is kneaded with a resin, the dispersibility of the mixture in the resin deteriorates, resulting in poor mixability. On the other hand, the mixture of the present invention contains fibrous cellulose in which some or all of the hydroxyl groups are substituted with carbamate groups, and powder that interacts with the fibrous cellulose, so that the fibrous cellulose is 55 Even if it exceeds parts by mass, high dispersibility can be maintained when the mixture is kneaded with the resin. Increasing the concentration of fibrous cellulose in the mixture is also preferable from the viewpoint that the amount of the mixture used to contain a desired proportion of fibrous cellulose in the composite resin can be reduced.

For the kneading treatment, for example, one or more selected from single-screw or multi-screw kneaders with two or more screws, mixing rolls, kneaders, roll mills, Banbury mixers, screw presses, dispersers, etc. are used. be able to. Among them, it is preferable to use a multi-screw kneader with two or more screws. Two or more multi-screw kneaders with two or more screws may be used in parallel or in series.

The temperature of the kneading treatment is higher than the glass transition point of the resin, and varies depending on the type of resin, but is preferably 80 to 280°C, more preferably 90 to 260°C, and more preferably 100 to 240°C. is particularly preferred.

At least one of a thermoplastic resin and a thermosetting resin can be used as the resin.

Examples of thermoplastic resins include polyolefins such as polypropylene (PP) and polyethylene (PE), polyester resins such as aliphatic polyester resins and aromatic polyester resins, polyacrylic resins such as polystyrene, methacrylates and acrylates, polyamide resins, One or more of polycarbonate resins, polyacetal resins and the like can be selected and used.

However, it is preferable to use at least one of polyolefin and polyester resin. Polypropylene is preferably used as the polyolefin. Furthermore, as polyester resins, aliphatic polyester resins such as polylactic acid and polycaprolactone can be exemplified, and aromatic polyester resins such as polyethylene terephthalate can be exemplified. It is preferable to use a polyester resin having

As the biodegradable resin, for example, one or more of hydroxycarboxylic acid-based aliphatic polyesters, caprolactone-based aliphatic polyesters, dibasic acid polyesters, and the like can be selected and used.

Hydroxycarboxylic acid-based aliphatic polyesters include, for example, homopolymers of hydroxycarboxylic acids such as lactic acid, malic acid, glucose acid, and 3-hydroxybutyric acid, and copolymers using at least one of these hydroxycarboxylic acids. One or two or more may be selected and used from among polymers and the like. However, it is preferable to use polylactic acid, a copolymer of lactic acid and the above hydroxycarboxylic acids other than lactic acid, polycaprolactone, and a copolymer of at least one of the above hydroxycarboxylic acids and caprolactone. It is particularly preferred to use

As the lactic acid, for example, L-lactic acid, D-lactic acid, or the like can be used, and these lactic acids may be used alone or two or more of them may be selected and used.

As the caprolactone-based aliphatic polyester, for example, one or more of polycaprolactone homopolymers and copolymers of polycaprolactone and the above hydroxycarboxylic acids can be selected and used. .

As the dibasic acid polyester, for example, one or more of polybutylene succinate, polyethylene succinate, polybutylene adipate and the like can be selected and used.

A biodegradable resin may be used individually by 1 type, or may use 2 or more types together.

Examples of thermosetting resins include phenol resins, urea resins, melamine resins, furan resins, unsaturated polyesters, diallyl phthalate resins, vinyl ester resins, epoxy resins, urethane resins, silicone resins, thermosetting polyimide resins, and the like. can be used. These resins can be used alone or in combination of two or more.

The blending ratio of fibrous cellulose and resin is preferably 1 part by mass or more of fibrous cellulose and 99 parts by mass or less of resin, more preferably 2 parts by mass or more of fibrous cellulose and 98 parts by mass or less of resin, and particularly preferably The fibrous cellulose is 3 parts by mass or more, and the resin is 97 parts by mass or less. Also, preferably 50 parts by mass or less of fibrous cellulose, 50 parts by mass or more of resin, more preferably 40 parts by mass or less of fibrous cellulose, 60 parts by mass or more of resin, and particularly preferably 30 parts by mass or less of fibrous cellulose. , resin is 70 parts by mass or more. In particular, when the fibrous cellulose is 10 to 50 parts by mass, the strength of the resin composition, particularly the bending strength and tensile modulus strength, can be remarkably improved.

In addition, the content ratio of the fibrous cellulose and the resin contained in the finally obtained resin composition is usually the same as the above mixing ratio of the fibrous cellulose and the resin.

If the difference in the solubility parameter (cal/cm ³ ) ^1/2 (SP value) of microfiber cellulose and resin, that is, the SP _MFC value of microfiber cellulose and the SP _POL value of resin, the difference in SP value = SP _MFC value -SP can be a _POL value. The SP value difference is preferably 10 to 0.1, more preferably 8 to 0.5, and particularly preferably 5 to 1. If the SP value difference exceeds 10, the microfiber cellulose will not be dispersed in the resin, and the reinforcing effect cannot be obtained. On the other hand, if the difference in SP value is less than 0.1, the microfiber cellulose will dissolve in the resin and will not function as a filler, failing to obtain a reinforcing effect. In this regard, the smaller the difference between the SP _POL value of the resin (solvent) and the SP _MFC value of the microfiber cellulose (solute), the greater the reinforcing effect.

The solubility parameter (cal/cm ³ ) ^1/2 (SP value) is a measure of the intermolecular force acting between a solvent and a solute. Solvents and solutes with closer SP values have higher solubility. .

(Molding process)
The kneaded product of fibrous cellulose-containing material and resin can be molded into a desired shape after kneading again if necessary. The size, thickness, shape, and the like of this molding are not particularly limited, and may be, for example, sheet-like, pellet-like, powder-like, fibrous-like, or the like.

The temperature during the molding process is equal to or higher than the glass transition point of the resin, and is, for example, 90 to 260°C, preferably 100 to 240°C, depending on the type of resin.

The kneaded product can be molded by, for example, mold molding, injection molding, extrusion molding, blow molding, foam molding, and the like. Alternatively, the kneaded product may be spun into a fibrous form and mixed with the above-described plant material or the like to form a mat or board. Mixing can be carried out by, for example, a method of simultaneous deposition by air laying.

As a device for molding the kneaded material, for example, one or two of injection molding machines, blow molding machines, blow molding machines, blow molding machines, compression molding machines, extrusion molding machines, vacuum molding machines, air pressure molding machines, etc. More than one species can be selected and used.

The above molding may be carried out after kneading, or the kneaded product may be cooled once, chipped using a crusher or the like, and then the chips may be put into a molding machine such as an extruder or an injection molding machine. can also be done. Of course, molding is not an essential requirement of the invention.

(Other compositions)
The fibrous cellulose inclusions may include cellulose nanofibers along with microfibrous cellulose. Cellulose nanofibers are fine fibers like microfiber cellulose, and have a role to complement microfiber cellulose for improving the strength of resin. However, if possible, it is preferable to use only microfiber cellulose without including cellulose nanofibers as fine fibers. The average fiber diameter (average fiber width, average diameter of single fibers) of cellulose nanofibers is preferably 4 to 100 nm, more preferably 10 to 80 nm.

The fibrous cellulose-containing material may also contain pulp. Pulp has the role of greatly improving the dewaterability of the cellulose fiber slurry. However, as in the case of cellulose nanofibers, it is most preferable not to mix pulp, that is, the content is 0% by mass.

In addition to fine fibers and pulp, resin compositions (composite resins) include kenaf, jute hemp, manila hemp, sisal hemp, ganpi, mitsumata, kozo, bananas, pineapples, coconut palms, corn, sugar cane, bagasse, coconut palms, papyrus, Fibers derived from plant materials obtained from various plants such as reeds, esparto, surviving grass, wheat, rice, bamboo, various conifers (such as cedar and cypress), broad-leaved trees, and cotton can be included, and are included. good too.

For the resin composition, for example, one or more selected from among antistatic agents, flame retardants, antibacterial agents, colorants, radical scavengers, foaming agents, etc., within a range that does not impede the effects of the present invention. can be added at These raw materials may be added to the fibrous cellulose dispersion, added during kneading of the fibrous cellulose and resin, added to the kneaded product, or added by other methods. good. However, from the viewpoint of production efficiency, it is preferable to add the fibrous cellulose and the resin during kneading.

The resin composition may contain an ethylene-α-olefin copolymer elastomer or a styrene-butadiene block copolymer as a rubber component. Examples of α-olefins include, for example, butene, isobutene, pentene, hexene, methyl-pentene, octene, decene, dodecene, and the like.

Next, examples of the present invention will be described.
Maleic anhydride-modified polypropylene (MAPP) with a uniform particle size or maleic anhydride-modified polypropylene (MAPP) with a mixture of different particle sizes was added to 1,570 g of microfiber cellulose with a solid content concentration of 2.8% by mass. 22.0 g was added and heated using a contact dryer heated to 140° C. to obtain a carbamate-modified microfiber cellulose inclusion. The moisture content of the carbamate-modified microfibrous cellulose inclusions was 5-22%.

The method for carbamate modification of the fiber was as follows.
That is, using softwood kraft pulp with a moisture content of 10% or less, an aqueous urea solution with a solid concentration of 10%, and an aqueous 20% citric acid solution, the mass ratio of pulp: urea: citric acid = 100: 50: 0 in terms of solid content. After mixing to .1, it was dried at 105°C. Next, heat treatment was performed at a predetermined reaction temperature and reaction time to obtain carbamate-modified pulp (carbamate-modified pulp). The resulting carbamate-modified pulp was diluted with distilled water and stirred, and the dehydration step was repeated twice. The washed carbamate-modified pulp is beaten using a beater until the ratio of less than 0.2 mm and the ratio of 0.2 to 0.6 mm reach a predetermined ratio, and carbamate-modified microfiber cellulose (carbamate MFC (fine fiber)) was obtained.

Also, 22.0 g of polypropylene powder was used in place of the maleic anhydride-modified polypropylene to obtain a carbamate-modified microfiber cellulose-containing material as a comparative example. The moisture content of the carbamate-modified microfibrous cellulose inclusions was 5-22%.

Polypropylene pellets were added to the carbamate-modified microfiber cellulose-containing material obtained as described above, and the ratio of carbamate-modified microfiber: other components = 10:90. to obtain a carbamate-modified microfiber cellulose composite resin with a fiber content of 10%.

The carbamate-modified microfiber cellulose composite resin obtained as described above was cut into cylinders with a diameter of 2 mm and a length of 2 mm with a pelleter, and a rectangular parallelepiped test piece (length 59 mm, width 9.6 mm, thickness 3.8 mm) was obtained at 180 ° C. ). The flexural modulus was examined for each specimen. The results are shown in Table 1 together with the particle size (particle diameter) of MAPP and the fiber size (fiber length) of fibrous cellulose according to the following criteria.

(flexural modulus)
The flexural modulus was measured according to JIS K7171:2008. In the table, the evaluation results are shown according to the following criteria.
When the bending elastic modulus of the resin itself is 1 and the bending elastic modulus (magnification) of the composite resin is 1.45 times or more: ○
When the bending elastic modulus of the resin itself is 1 and the bending elastic modulus (magnification) of the composite resin is 1.40 times or more and less than 1.45 times: △

If the bending elastic modulus (magnification) of the composite resin is less than 1.40 times assuming that the bending elastic modulus of the resin itself is 1: ×

INDUSTRIAL APPLICABILITY The present invention can be used as a fibrous cellulose-containing material, a fibrous cellulose composite resin, and a method for producing a fibrous cellulose-containing material. For example, fibrous cellulose composite resins are used for interior materials, exterior materials, structural materials, etc. of transportation equipment such as automobiles, trains, ships, and airplanes; Parts, etc.; Housings, structural materials, internal parts, etc. of mobile communication devices such as mobile phones; Structural materials, internal parts, etc.; interior materials, exterior materials, structural materials, etc. for buildings and furniture; office equipment, etc. such as stationery; Available.

TECHNICAL FIELD The present invention relates to a fibrous cellulose-containing material, a fibrous cellulose composite resin, and a method for producing a fibrous cellulose-containing material.

In recent years, the use of fine fibers such as cellulose nanofibers and microfiber cellulose (microfibrillated cellulose) as reinforcing materials for resins has attracted attention. However, since the fine fibers are hydrophilic and the resin is hydrophobic, there is a problem in the dispersibility of the fine fibers when using the fine fibers as a reinforcing material for the resin. Accordingly, the present inventors proposed substituting the hydroxy groups of fine fibers with carbamate groups (see Patent Document 1). According to this proposal, the dispersibility of the fine fibers is improved, thereby improving the reinforcing effect of the resin. However, fine fibers aggregate during drying, but since this aggregation is strong, there is a problem in terms of dispersibility when using dried fine fibers as a reinforcing material for resins.

JP 2019-1876 A

The main problem to be solved by the present invention is to provide a fibrous cellulose-containing material that is excellent in dispersibility even when dried, a method for producing the same, and a fibrous cellulose composite resin that is excellent in strength.

In the conventional development, for example, the development of the above-mentioned patent document, the focus is placed on the dispersibility of fine fibers when they are held in a dispersion state, and esterification, etherification, amidation, sulfidation, etc. , found that the introduction of carbamate (carbamation) is superior among many modification methods. In contrast, the present invention focuses on the dispersibility of fine fibers when the fine fibers are once dried and then mixed with a resin. The inventors have found that the above-mentioned problems can be solved by pursuing other substances and physical properties to be used together with them, and have arrived at the idea. The means conceived in this way are as follows.

(Means according to claim 1)
A fibrous cellulose inclusion added to the resin,
The fibrous cellulose has an average fiber width of 0.1 to 19 μm, and some or all of the hydroxyl groups are substituted with carbamate groups,
comprising a powder that interacts with the fibrous cellulose ;
The interacting powder has a 90% particle size/10% particle size of 2 to 200.
A fibrous cellulose-containing material characterized by:

(Means according to claim 2)
the interacting powder has an arithmetic standard deviation of 10-1000 μm ;
The fibrous cellulose inclusion according to claim 1.

(Means according to claim 3)
The volume average particle diameter of the interacting powder is 50 to 750 μm, and the volume average particle diameter (μm) of the interacting powder/average fiber length (μm) of the fibrous cellulose is 0.005 to 5000. be,
The fibrous cellulose containing material according to claim 1 or claim 2.

(Means according to claim 4)
The fibrous cellulose has a fiber length of less than 0.2 mm in a proportion of 5% or more and a fiber length of 0.2 to 0.6 mm in a proportion of 10% or more.
The fibrous cellulose-containing material according to any one of claims 1-3.

(Means according to claim 5)
The fibrous cellulose has an average fiber length of 1.0 mm or less, an average fiber width of 10 μm or less, and a fibrillation rate of 2.5% or more.
The fibrous cellulose-containing material according to any one of claims 1-4.

(Means according to claim 6)
The interacting powder is an acid-modified resin having an acid value of 2.0% or more,
The fibrous cellulose-containing material according to any one of claims 1-5.

(Means according to claim 7)
wherein said interacting powder is maleic anhydride modified polypropylene;
The fibrous cellulose-containing material according to any one of claims 1-6.

(Means according to claim 8)
A fibrous cellulose composite resin in which fibrous cellulose and resin are mixed,
The fibrous cellulose-containing material according to any one of claims 1 to 7 is used as the fibrous cellulose,
A fibrous cellulose composite resin characterized by:

(Means according to claim 9)
Fibrous cellulose in which some or all of the hydroxyl groups have been substituted with carbamate groups is defibrated so that the average fiber width is 0.1 to 19 μm, and the fibrous cellulose and the fibrous cellulose have a particle diameter of 90%/10%. mixing with 2 to 200 interacting powders to obtain a mixture;
drying the mixture,
A method for producing a fibrous cellulose-containing material, characterized by:

INDUSTRIAL APPLICABILITY According to the present invention, a fibrous cellulose-containing material excellent in dispersibility even when dried, a method for producing the same, and a fibrous cellulose composite resin excellent in strength are obtained.

Next, a mode for carrying out the invention will be described. Note that this embodiment is an example of the present invention. The scope of the present invention is not limited to the scope of this embodiment.

The fibrous cellulose-containing material of the present embodiment is added to a resin, and the fibrous cellulose (hereinafter also referred to as "cellulose fiber") has an average fiber width of 0.1 to 19 μm and a hydroxyl group (—OH groups) are partially or entirely substituted with carbamate groups. In addition, the fibrous cellulose-containing material contains powder that interacts with fibrous cellulose (hereinafter also simply referred to as "interacting powder"). The powder is preferably an acid-modified resin whose acid groups ionically bond with some or all of the carbamate groups. Moreover, a fibrous cellulose composite resin is obtained by adding this fibrous cellulose-containing material to a resin. Furthermore, in the method for producing a fibrous cellulose-containing material, fibrous cellulose in which some or all of the hydroxyl groups have been substituted with carbamate groups is defibrated so that the average fiber width is 0.1 to 19 μm, and the fibers are A powder that interacts with the cellulose is added to obtain a mixed liquid, and the mixed liquid is dried. A detailed description will be given below.

(fibrous cellulose)
The fibrous cellulose, which is fine fibers in this embodiment, is microfiber cellulose (microfibrillated cellulose) having an average fiber diameter of 0.1 to 19 μm. Microfiber cellulose significantly improves the reinforcing effect of the resin. Microfiber cellulose is also easier to modify with carbamate groups (carbamate) than cellulose nanofibers, which are also fine fibers. However, it is more preferred to carbamate the cellulosic feedstock prior to micronization, in which case microfiber cellulose and cellulose nanofibers are equivalent.

In this embodiment, microfiber cellulose means fibers having a larger average fiber width than cellulose nanofibers. Specifically, the average fiber diameter (width) is, for example, 0.1 to 19 μm, preferably 0.2 to 10 μm, more preferably over 0.5 to 10 μm. If the average fiber diameter of the fibrous cellulose is less than 0.1 μm (below), it is no different from cellulose nanofibers, and there is a risk that the effect of improving the strength (especially bending elastic modulus) of the resin cannot be sufficiently obtained. . In addition, defibration takes a long time, and a large amount of energy is required. Furthermore, the dewaterability of the cellulose fiber slurry deteriorates. When the dehydration property deteriorates, a large amount of energy is required for drying, and if a large amount of energy is applied to drying, the fibrous cellulose may be thermally degraded, resulting in a decrease in strength. In addition, when defibration is performed to an average fiber diameter of less than 0.1 μm, the variation in the fiber length of the fibrous cellulose becomes small, making it difficult to exhibit the effects of the present embodiment that define the particle size distribution of the interacting powder. .

On the other hand, if the average fiber diameter of the fibrous cellulose exceeds (exceeds) 19 μm, it is no different from that of pulp, and the reinforcing effect may not be sufficient. In addition, when the average fiber diameter exceeds 19 μm, the variation in fiber length of the fibrous cellulose is small, and the effect of the present embodiment that defines the particle size distribution of the interacting powder is difficult to exhibit. In addition, when the average fiber diameter is 10 μm or less, the average fiber length is 1.0 mm or less and the fibrillation ratio is 2.5% or more.

The mode diameter (width) of fibrous cellulose is preferably 0.1 to 19 μm, more preferably 0.5 to 10 μm, particularly preferably 1 to 6 μm. In this regard, in the present embodiment in which the fiber length of the fibrous cellulose varies as described later, fibers with a large fiber width are mixed in a certain proportion during defibration, so the fibrous cellulose is specified by the average fiber diameter. It is preferable to specify the mode diameter with the largest number. From this point of view, if the mode diameter is less than 0.1 μm, the proportion of cellulose nanofibers tends to increase, and the cellulose nanofibers aggregate with each other, possibly resulting in an insufficient reinforcing effect. On the other hand, if the mode diameter exceeds 19 μm, the ratio of pulp tends to increase, and it can be said that the reinforcing effect may not be sufficient.

The method for measuring the average fiber diameter of fine fibers (microfiber cellulose and cellulose nanofiber) is as follows.
First, 100 ml of an aqueous dispersion of fine fibers having a solid concentration of 0.01 to 0.1% by mass is filtered through a Teflon (registered trademark) membrane filter, and the solvent is replaced once with 100 ml of ethanol and 3 times with 20 ml of t-butanol. do. It is then freeze-dried and coated with osmium to form a sample. This sample is observed with an electron microscope SEM image at a magnification of 3,000 times to 30,000 times depending on the width of the constituent fibers. Specifically, two diagonal lines are drawn on the observation image, and three straight lines passing through the intersections of the diagonal lines are arbitrarily drawn. Furthermore, the width of a total of 100 fibers intersecting with these three straight lines is visually measured. Then, the median diameter of the measured value is taken as the average fiber diameter.

In addition, the mode diameter of fine fibers is measured by a fiber analyzer "FS5" manufactured by Valmet.

By the way, when the fibrous cellulose is microfibrous cellulose, it has a characteristic that the variation in fiber length and the like increases. This is for the following reasons.
First, pulp is produced, for example, by boiling chips with alkali under pressure and then loosening them when the pressure returns to normal, without mechanical fibrillation. Therefore, wood cells are isolated as they are to form a pulp, and the fiber length and the like are relatively uniform. In addition, the cellulose nanofibers consist of fibers with independent fluffing portions, and the fluffing portions of the cellulose microfibers are separated independently. Therefore, the fiber length and the like are relatively uniform. On the other hand, the microfiber cellulose is in a stage where the fibers are fluffing due to the application of a mechanical defibration force to the pulp, and therefore the distribution of the fiber length and the like is widened.

Microfiber cellulose usually has a fiber length of less than 0.2 mm in a proportion of 5% or more and a fiber length of 0.2 to 0.6 mm in a proportion of 10% or more, preferably a fiber length of less than 0.2 mm. 8% or more, a fiber length of 0.2 to 0.6 mm is 13% or more, more preferably a fiber length of less than 0.2 mm is 20% or more, and a fiber length is 0.2 to 0.2 mm. A ratio of 6 mm is 16% or more. When the fiber length of the microfiber cellulose is varied as described above, the action and effect of the present embodiment that regulates the particle size distribution of the interacting powder are exhibited fully.

In the above, if the proportion of fibers having a fiber length of less than 0.2 mm is too large, the entanglement with interacting powder having a large particle size becomes insufficient, which may lead to a decrease in dispersibility. On the other hand, if the proportion of fibers having a length of more than 0.6 mm is too high, the entanglement with the interacting powder of small particle size becomes insufficient, which may lead to a decrease in dispersibility.

As described above, the variation in the fiber length, etc. of microfiber cellulose is relatively large. Then, there is a possibility that the reinforcing effect of the resin as the fiber itself is inferior. Therefore, the proportion of fibrous cellulose having a fiber length of 0.2 to 0.6 mm is preferably 10 to 90%, more preferably 14 to 70%, and particularly preferably 16 to 50%. If the proportion of fibers having a length of 0.2 to 0.6 mm is less than 14%, the entanglement with the interacting powder will be insufficient, and as a result, there is a possibility that the reinforcing effect will not be exhibited sufficiently.

Microfiber cellulose can be obtained by defibrating (refining) a cellulose raw material (hereinafter also referred to as "raw material pulp"). Raw material pulp includes, for example, wood pulp made from broad-leaved trees, coniferous trees, etc., non-wood pulp made from straw, bagasse, cotton, hemp, pistil fibers, etc., and waste paper pulp made from recovered waste paper, waste paper, etc. (DIP) or the like can be selected and used. The various raw materials described above may be, for example, in the form of pulverized (powdered) material such as cellulose powder.

However, in order to avoid contamination with impurities as much as possible, it is preferable to use wood pulp as the raw material pulp. As the wood pulp, for example, one or more of chemical pulps such as hardwood kraft pulp (LKP) and softwood kraft pulp (NKP), mechanical pulp (TMP), etc. can be selected and used.

The hardwood kraft pulp may be bleached hardwood kraft pulp, unbleached hardwood kraft pulp, or semi-bleached hardwood kraft pulp. Similarly, the softwood kraft pulp may be softwood bleached kraft pulp, softwood unbleached kraft pulp, or softwood semi-bleached kraft pulp.

Examples of mechanical pulp include stone ground pulp (SGP), pressure stone ground pulp (PGW), refiner ground pulp (RGP), chemi ground pulp (CGP), thermo ground pulp (TGP), ground pulp (GP), One or more of thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), refiner mechanical pulp (RMP), bleached thermomechanical pulp (BTMP) and the like can be selected and used.

The raw pulp can be pretreated by chemical means prior to defibration. Examples of chemical pretreatments include hydrolysis of polysaccharides with acid (acid treatment), hydrolysis of polysaccharides with enzymes (enzyme treatment), swelling of polysaccharides with alkali (alkali treatment), and oxidation of polysaccharides with an oxidizing agent ( oxidation treatment), reduction of polysaccharides with a reducing agent (reduction treatment), and the like. However, as the chemical pretreatment, it is preferable to perform enzyme treatment, and in addition, it is more preferable to perform one or more treatments selected from acid treatment, alkali treatment, and oxidation treatment. The enzymatic treatment will be described in detail below.

At least one of a cellulase enzyme and a hemicellulase enzyme is preferably used as the enzyme used for the enzymatic treatment, and it is more preferable to use both together. The use of these enzymes makes the fibrillation of cellulosic raw materials easier. Cellulase enzymes cause decomposition of cellulose in the presence of water. In addition, hemicellulase enzymes cause decomposition of hemicellulose in the presence of water.

Cellulase enzymes include, for example, Trichoderma genus, Acremonium genus, Aspergillus genus, Phanerochaete genus, Trametes genus genus Humicola, genus Bacillus, genus Schizophyllum, genus Streptomyces, genus Pseudomonas, etc. Enzymes can be used. These cellulase enzymes can be purchased as reagents or commercial products. Commercially available products include, for example, cellulucine T2 (manufactured by HPI), Meicerase (manufactured by Meiji Seika Co., Ltd.), Novozym 188 (manufactured by Novozym), Multifect CX10L (manufactured by Genencore), cellulase enzyme GC220 (manufactured by Genencore). ) etc. can be exemplified.

Both EG (endoglucanase) and CBH (cellobiohydrolase) can be used as cellulase enzymes. EG and CBH may be used alone or in combination. It may also be used in combination with a hemicellulase enzyme.

Examples of hemicellulase enzymes that can be used include xylanase, an enzyme that degrades xylan, mannase, an enzyme that degrades mannan, and arabanase, an enzyme that degrades araban. can. Pectinase, which is an enzyme that degrades pectin, can also be used.

Hemicellulose is a polysaccharide excluding pectins present between cellulose microfibrils in plant cell walls. Hemicelluloses are very diverse and differ between wood types and cell wall layers. Glucomannan is the main component in the secondary walls of coniferous trees, and 4-O-methylglucuronoxylan is the main component in the secondary walls of hardwoods. Therefore, when obtaining fine fibers from softwood bleached kraft pulp (NBKP), it is preferable to use mannase. In addition, when obtaining fine fibers from hardwood bleached kraft pulp (LBKP), it is preferable to use xylanase.

The amount of enzyme added to the cellulose raw material is determined, for example, by the type of enzyme, the type of wood used as the raw material (coniferous or hardwood), the type of mechanical pulp, and the like. However, the amount of enzyme added to the cellulose raw material is preferably 0.1 to 3% by mass, more preferably 0.3 to 2.5% by mass, and particularly preferably 0.5 to 2% by mass. If the added amount of the enzyme is less than 0.1% by mass, there is a possibility that the effect of the addition of the enzyme cannot be sufficiently obtained. On the other hand, if the added amount of the enzyme exceeds 3% by mass, cellulose may be saccharified and the yield of fine fibers may decrease. Moreover, there is also a problem that an improvement in the effect commensurate with an increase in the amount added cannot be recognized.

When a cellulase enzyme is used as the enzyme, the pH during the enzyme treatment is preferably in the weakly acidic range (pH=3.0 to 6.9) from the viewpoint of the reactivity of the enzyme reaction. On the other hand, when a hemicellulase enzyme is used as the enzyme, the pH during the enzyme treatment is preferably in the weakly alkaline range (pH=7.1 to 10.0).

The temperature during enzyme treatment is preferably 30 to 70°C, more preferably 35 to 65°C, and particularly preferably 40 to 60°C, regardless of whether a cellulase enzyme or a hemicellulase enzyme is used as the enzyme. . If the temperature during the enzyme treatment is 30° C. or higher, the enzyme activity is less likely to decrease and the treatment time can be prevented from becoming longer. On the other hand, if the temperature during the enzyme treatment is 70° C. or lower, deactivation of the enzyme can be prevented.

The enzymatic treatment time is determined by, for example, the type of enzyme, the temperature of the enzymatic treatment, the pH at the time of the enzymatic treatment, and the like. However, the general enzymatic treatment time is 0.5 to 24 hours.

After enzymatic treatment, the enzyme is preferably deactivated. Methods for inactivating the enzyme include, for example, a method of adding an alkaline aqueous solution (preferably pH 10 or higher, more preferably pH 11 or higher), a method of adding hot water at 80 to 100°C, and the like.

Next, the method of alkali treatment will be described.
Alkaline treatment prior to fibrillation dissociates some of the hydroxyl groups of hemicellulose and cellulose in the pulp, anionizing the molecules, weakening intramolecular and intermolecular hydrogen bonds, and promoting the dispersion of cellulose raw materials during fibrillation. be.

Alkali used for alkali treatment include, for example, sodium hydroxide, lithium hydroxide, potassium hydroxide, aqueous ammonia solution, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, and the like. An organic alkali or the like can be used. However, from the viewpoint of production cost, it is preferable to use sodium hydroxide.

If enzymatic treatment, acid treatment, or oxidation treatment is performed prior to defibration, the water retention of the microfiber cellulose can be lowered, the crystallinity can be increased, and the homogeneity can be enhanced. In this regard, when the water retention of the microfiber cellulose is low, it becomes easy to dewater, and the dewaterability of the cellulose fiber slurry is improved.

When the raw material pulp is subjected to enzyme treatment, acid treatment, or oxidation treatment, the hemicellulose and amorphous regions of cellulose in the pulp are decomposed. As a result, the defibration energy can be reduced, and the uniformity and dispersibility of the cellulose fibers can be improved. However, since pretreatment reduces the aspect ratio of the microfiber cellulose, it is preferable to avoid excessive pretreatment when used as a reinforcing material for resins.

For defibration of raw material pulp, for example, beaters, high-pressure homogenizers, homogenizers such as high-pressure homogenizers, grinders, stone mills such as grinders, single-screw kneaders, multi-screw kneaders, kneader refiners, jet mills, etc. It can be carried out by beating the raw material pulp using However, it is preferable to use a refiner or a jet mill.

The average fiber length (average length of single fibers) of the microfiber cellulose is preferably 0.10 to 2.00 mm, more preferably 0.12 to 1.50 mm, and particularly preferably 0.15 to 1.00 mm. be. If the average fiber length is less than 0.10 mm, a three-dimensional network cannot be formed between the fibers, and there is a risk that the reinforcing effect (especially the flexural modulus) of the composite resin will decrease. It may also not entangle well with interacting powders. On the other hand, if the average fiber length exceeds 2.00 mm, there is a risk that the reinforcing effect will be insufficient because the fiber length is the same as that of raw material pulp. Also, the fibers can clump together and not be sufficiently entangled with the interacting powder.

The average fiber length of the cellulose raw material, which is the raw material of the microfiber cellulose, is preferably 0.50 to 5.00 mm, more preferably 1.00 to 3.00 mm, and particularly preferably 1.50 to 2.50 mm. If the average fiber length of the cellulose raw material is less than 0.50 mm, the reinforcing effect of the resin may not be sufficiently obtained during defibration treatment. On the other hand, if the average fiber length exceeds 5.00 mm, it may be disadvantageous in terms of production cost during fibrillation.

The average fiber length of microfiber cellulose can be arbitrarily adjusted by, for example, selection of raw material pulp, pretreatment, defibration, and the like.

The aspect ratio of the microfiber cellulose is preferably 2-15,000, more preferably 10-10,000. If the aspect ratio is less than 2, a three-dimensional network cannot be constructed, so even if the average fiber length exceeds 0.10 mm, the reinforcing effect may be insufficient. In addition, if the aspect ratio is less than 2, the number of points that can interact with the interacting powder having a sphere-like shape is too small. can not be sufficiently exhibited, and the reinforcing effect may be insufficient. On the other hand, if the aspect ratio exceeds 15,000, there is a risk that the cellulose microfibers will be entangled with each other, resulting in insufficient dispersion in the resin. In addition, there is a possibility that the fibers interact with each other and the interaction with the interacting powder does not occur sufficiently, resulting in an insufficient reinforcing effect.

The aspect ratio is the value obtained by dividing the average fiber length by the average fiber width. As the aspect ratio increases, the number of locations where catching occurs increases, so that the reinforcing effect increases.

The fibrillation rate of the microfiber cellulose is preferably 1.0-30.0%, more preferably 1.5-20.0%, particularly preferably 2.5-15.0%. If the fibrillation rate exceeds 30.0%, the contact area with water becomes too large, so even if defibration is performed in a range in which the average fiber width remains at 0.1 μm or more, dehydration may become difficult. be. On the other hand, if the fibrillation rate exceeds 30.0%, the surface area becomes too large and the fibers tend to retain water, which may make it difficult to interact with the interacting powder. On the other hand, if the fibrillation rate is less than 1.0%, hydrogen bonding between fibrils is reduced, and a strong three-dimensional network may not be formed. Also, if the fibrillation rate is less than 2.5%, there is a tendency for poor clinging to interacting powders.

The fiber length and fibrillation rate of the fiber are measured with a fiber analyzer "FS5" manufactured by Valmet.

The crystallinity of the microfibrous cellulose is preferably 50% or higher, more preferably 55% or higher, particularly preferably 60% or higher. When the degree of crystallinity is less than 50%, although the miscibility with other cellulose fibers such as pulp and cellulose nanofibers is improved, the strength of the fibers themselves is lowered, so the strength of the resin cannot be improved. There is a risk. On the other hand, the crystallinity of the microfibrous cellulose is preferably 95% or less, more preferably 90% or less, particularly preferably 85% or less. If the degree of crystallinity exceeds 95%, the ratio of strong hydrogen bonds in the molecule increases, the fiber itself becomes rigid, and the dispersibility deteriorates.

The crystallinity of microfiber cellulose can be arbitrarily adjusted by, for example, selection of raw material pulp, pretreatment, and refining treatment.

Crystallinity is a value measured according to JIS K 0131 (1996).

The pulp viscosity of the microfiber cellulose is preferably 2 cps or greater, more preferably 4 cps or greater. If the pulp viscosity of the microfiber cellulose is less than 2 cps, it may be difficult to suppress the aggregation of the microfiber cellulose. Further, if the pulp viscosity is less than 2 cps, the reinforcing properties of the resin may be insufficient even if the interaction with the interacting powder is exhibited.

Pulp viscosity is a value measured according to TAPPI T230.

The freeness of the microfibrous cellulose is preferably 500 ml or less, more preferably 300 ml or less, particularly preferably 100 ml or less. If the freeness of the microfiber cellulose exceeds 500 ml, the effect of improving the strength of the resin may not be obtained sufficiently. In addition, the entanglement with the interacting powder becomes poor, and there is a possibility that the agglomeration of the fibers cannot be sufficiently suppressed.

Freeness is a value measured according to JIS P8121-2 (2012).

The zeta potential of the microfiber cellulose is preferably −150 to 20 mV, more preferably −100 to 0 mV, particularly preferably −80 to −10 mV. If the zeta potential is less than -150 mV, the compatibility with the resin may be significantly reduced and the reinforcing effect may be insufficient. On the other hand, when the zeta potential exceeds 20 mV, the dispersion stability may deteriorate.

The water retention of the microfibrous cellulose is preferably 80-400%, more preferably 90-350%, particularly preferably 100-300%. If the water retention is less than 80%, the reinforcing effect may be insufficient because it is the same as the raw material pulp. On the other hand, if the water retention exceeds 400%, the dewatering property tends to be poor and aggregation tends to occur. In this regard, the water retention of the microfiber cellulose can be lowered by substituting the hydroxy group of the fiber with a carbamate group, and the dehydration and drying properties can be enhanced.

The water retention of microfiber cellulose can be arbitrarily adjusted by, for example, selection of raw material pulp, pretreatment, defibration, and the like.

The degree of water retention is determined by JAPAN TAPPI No. 26 (2000).

The microfibrous cellulose of this form has carbamate groups. There is no particular limitation on how it is determined to have a carbamate group. For example, the cellulose raw material may be carbamate to have carbamate groups, or the microfiber cellulose (micronized cellulose raw material) may be carbamate to have carbamate groups. .

In addition, having a carbamate group means a state in which carbamate (ester of carbamic acid) is introduced into fibrous cellulose. A carbamate group is a group represented by --O--CO--NH--, for example, a group represented by --O--CO--NH ₂ , --O--CONHR, --O--CO--NR ₂ and the like. That is, the carbamate group can be represented by the following structural formula (1).

Here, each R is independently a saturated straight-chain hydrocarbon group, a saturated branched-chain hydrocarbon group, a saturated cyclic hydrocarbon group, an unsaturated straight-chain hydrocarbon group, an unsaturated branched-chain hydrocarbon group, It is at least one of an aromatic group and a derivative group thereof.

Examples of saturated linear hydrocarbon groups include linear alkyl groups having 1 to 10 carbon atoms such as methyl, ethyl and propyl groups.

Examples of saturated branched hydrocarbon groups include branched chain alkyl groups having 3 to 10 carbon atoms such as isopropyl group, sec-butyl group, isobutyl group and tert-butyl group.

Examples of saturated cyclic hydrocarbon groups include cycloalkyl groups such as cyclopentyl, cyclohexyl and norbornyl groups.

Examples of unsaturated linear hydrocarbon groups include linear alkenyl groups having 2 to 10 carbon atoms such as ethenyl, propen-1-yl, propen-3-yl, ethynyl, and propyne-1. -yl group, propyn-3-yl group and other linear alkynyl groups having 2 to 10 carbon atoms.

Examples of unsaturated branched hydrocarbon groups include branched chain alkenyl groups having 3 to 10 carbon atoms such as propen-2-yl group, buten-2-yl group and buten-3-yl group, butyne-3 A branched alkynyl group having 4 to 10 carbon atoms such as -yl group can be mentioned.

Examples of aromatic groups include phenyl group, tolyl group, xylyl group, naphthyl group and the like.

As the derivative group, the above saturated straight-chain hydrocarbon group, saturated branched-chain hydrocarbon group, saturated cyclic hydrocarbon group, unsaturated straight-chain hydrocarbon group, unsaturated branched-chain hydrocarbon group and aromatic group Groups in which one or more hydrogen atoms possessed are substituted with a substituent (eg, a hydroxy group, a carboxy group, a halogen atom, etc.) can be mentioned.

In microfibrous cellulose with carbamate groups (carbamate groups introduced), some or all of the more polar hydroxy groups are replaced with relatively less polar carbamate groups. Therefore, microfibrous cellulose with carbamate groups has low hydrophilicity and high affinity with low polar resins and the like. As a result, the microfiber cellulose having carbamate groups has excellent uniform dispersibility with the resin. Also, slurries of microfibrous cellulose with carbamate groups are less viscous and easier to handle.

The substitution ratio of carbamate groups to hydroxy groups of the microfiber cellulose is preferably 1.0 to 5.0 mmol/g, more preferably 1.2 to 3.0 mmol/g, particularly preferably 1.5 to 2.0 mmol/g. is g. When the substitution rate is 1.0 mmol/g or more, the effect of introducing carbamate, particularly the effect of improving the bending elongation of the resin, can be reliably exhibited. On the other hand, if the substitution rate exceeds 5.0 mmol/g, the cellulose fibers will not be able to maintain the shape of the fibers, and there is a risk that the reinforcing effect of the resin will not be obtained sufficiently.

The carbamate group substitution rate (mmol/g) refers to the amount of carbamate groups contained per 1 g of the cellulose raw material having carbamate groups. Cellulose is a polymer having anhydroglucose as a structural unit, and has three hydroxy groups per structural unit.

<Carbamate formation>
Regarding the point of introducing carbamate into microfiber cellulose (the cellulose raw material when carbamate conversion is performed before fibrillation; hereinafter the same applies, and may also be referred to as "microfiber cellulose, etc.") (carbamate conversion), as described above. There are a method in which a cellulose raw material is carbamate-ized and then pulverized, and a method in which a cellulose raw material is pulverized and then carbamate-ized. In this regard, in this specification, defibration of the cellulose raw material is described first, and then carbamate formation (modification) is described. However, defibration and carbamate can be performed either first. However, it is preferable to perform carbamate formation first and then defibrate. This is because the cellulose raw material before defibration has a high dehydration efficiency, and the cellulose raw material is easily defibrated by the heating accompanying carbamate formation.

The process of carbamating microfiber cellulose or the like can be divided primarily into, for example, a mixing process, a removal process, and a heat treatment. In addition, the mixing treatment and the removal treatment can be collectively referred to as an adjustment treatment for preparing a mixture to be subjected to heat treatment.

In the mixing process, microfiber cellulose or the like (as described above, it may be a cellulose raw material, hereinafter the same) and urea and / or a derivative of urea (hereinafter also simply referred to as "urea etc.") are mixed as a dispersion medium. Mix inside.

Examples of urea and urea derivatives include urea, thiourea, biuret, phenylurea, benzylurea, dimethylurea, diethylurea, tetramethylurea, and compounds in which hydrogen atoms of urea are substituted with alkyl groups. can. These urea and urea derivatives can be used singly or in combination. However, it is preferred to use urea.

The lower limit of the mixing mass ratio of urea etc. to microfiber cellulose etc. (urea etc./microfiber cellulose etc.) is preferably 10/100, more preferably 20/100. On the other hand, the upper limit is preferably 300/100, more preferably 200/100. By setting the mixing mass ratio to 10/100 or more, the efficiency of carbamate formation is improved. On the other hand, even if the mixing mass ratio exceeds 300/100, carbamate formation plateaus.

The dispersion medium is usually water. However, other dispersion media such as alcohols and ethers, and mixtures of water and other dispersion media may also be used.

In the mixing process, for example, microfiber cellulose or the like and urea or the like are added to water, microfiber cellulose or the like is added to an aqueous solution of urea or the like, or urea or the like is added to a slurry containing microfiber cellulose or the like. may Moreover, in order to mix uniformly, you may stir after addition. Further, the dispersion containing microfiber cellulose or the like and urea or the like may contain other ingredients.

In the removal treatment, the dispersion medium is removed from the dispersion containing microfiber cellulose and the like and urea and the like obtained in the mixing treatment. By removing the dispersion medium, urea and the like can be efficiently reacted in the subsequent heat treatment.

The removal of the dispersion medium is preferably carried out by volatilizing the dispersion medium by heating. According to this method, only the dispersion medium can be efficiently removed while leaving components such as urea.

The lower limit of the heating temperature in the removal treatment is preferably 50°C, more preferably 70°C, and particularly preferably 90°C when the dispersion medium is water. By setting the heating temperature to 50° C. or higher, the dispersion medium can be efficiently volatilized (removed). On the other hand, the upper limit of the heating temperature is preferably 120°C, more preferably 100°C. If the heating temperature exceeds 120° C., the dispersion medium and urea may react with each other and urea may decompose alone.

The heating time in the removal treatment can be appropriately adjusted according to the solid content concentration of the dispersion. Specifically, it is, for example, 6 to 24 hours.

In the heat treatment following the removal treatment, a mixture of microfiber cellulose or the like and urea or the like is heat treated. In this heat treatment, some or all of the hydroxy groups of the microfiber cellulose or the like react with urea or the like and are substituted with carbamate groups. More specifically, when urea or the like is heated, it decomposes into isocyanic acid and ammonia as shown in the following reaction formula (1). Isocyanic acid is highly reactive and, for example, forms a carbamate group on the hydroxyl group of cellulose as shown in the following reaction formula (2).
NH ₂ -CO-NH ₂ →H-N=C=O + NH ₃ (1)
Cell-OH + H-N=C=O → Cell-O-CO-NH ₂ (2)
The lower limit of the heating temperature in the heat treatment is preferably 120°C, more preferably 130°C, particularly preferably the melting point of urea (about 134°C) or higher, still more preferably 140°C, most preferably 150°C. By setting the heating temperature to 120° C. or higher, carbamate formation is efficiently performed. The upper limit of the heating temperature is preferably 200°C, more preferably 180°C, and particularly preferably 170°C. If the heating temperature exceeds 200° C., the microfiber cellulose or the like may be decomposed and the reinforcing effect may be insufficient.

The lower limit of the heating time in the heat treatment is preferably 1 minute, more preferably 5 minutes, particularly preferably 30 minutes, still more preferably 1 hour, most preferably 2 hours. By setting the heating time to 1 minute or longer, the carbamate reaction can be reliably carried out. On the other hand, the upper limit of the heating time is preferably 15 hours, more preferably 10 hours. If the heating time exceeds 15 hours, it is not economical, and 15 hours is sufficient for carbamate formation.

Prolonged heating time, however, invites deterioration of the cellulose fibers. Therefore, the pH condition in the heat treatment becomes important. The pH is preferably pH 9 or higher, more preferably pH 9-13, and particularly preferably pH 10-12 under alkaline conditions. Also, as a second best measure, pH 7 or less, preferably pH 3 to 7, particularly preferably pH 4 to 7, acidic or neutral conditions. Under neutral conditions of pH 7 to 8, the average fiber length of the cellulose fibers may be shortened, and the reinforcing effect of the resin may be inferior. On the other hand, under alkaline conditions of pH 9 or higher, the reactivity of the cellulose fibers increases, the reaction with urea and the like is promoted, and the carbamate reaction proceeds efficiently. can be done. On the other hand, under acidic conditions of pH 7 or less, the reaction of decomposing urea and the like into isocyanic acid and ammonia proceeds, and the reaction to cellulose fibers is accelerated, resulting in an efficient carbamate reaction. can be secured to However, if possible, it is preferable to heat-treat under alkaline conditions. This is because acid hydrolysis of cellulose may proceed under acidic conditions.

The pH can be adjusted by adding an acidic compound (eg, acetic acid, citric acid, etc.) or an alkaline compound (eg, sodium hydroxide, calcium hydroxide, etc.) to the mixture.

As a device for heating in the heat treatment, for example, a hot air dryer, a paper machine, a dry pulp machine, or the like can be used.

The heat-treated mixture may be washed. This washing may be performed with water or the like. By this washing, unreacted and remaining urea and the like can be removed.

(slurry)
The microfiber cellulose is optionally dispersed in an aqueous medium to form a dispersion (slurry). It is particularly preferred that the entire amount of the aqueous medium is water, but it is also possible to use an aqueous medium that is partly another liquid that is compatible with water. Other liquids that can be used include lower alcohols having 3 or less carbon atoms.

The solid content concentration of the slurry is preferably 0.1-10.0% by mass, more preferably 0.5-5.0% by mass. If the solid content concentration is less than 0.1% by mass, excessive energy may be required during dehydration and drying. On the other hand, when the solid content concentration exceeds 10.0% by mass, the fluidity of the slurry itself is lowered, and when a dispersant is used, there is a possibility that uniform mixing may not be possible.

(interacting powders)
The fibrous cellulose inclusion of this form comprises a powder that interacts with fibrous cellulose. By including the interacting powder in the fibrous cellulose-containing material, the fibrous cellulose can be brought into a form capable of exhibiting the reinforcing properties of the resin. That is, when fibrous cellulose is used as a slurry, it is preferable to remove the aqueous medium contained in the slurry before compounding with the resin. However, when the aqueous medium is removed, the cellulose may irreversibly aggregate due to hydrogen bonding, making it impossible to sufficiently exhibit the reinforcing effect of the fiber. Therefore, by including powder that interacts with the fibrous cellulose slurry, hydrogen bonding between celluloses is physically inhibited. Further, in the case of non-interacting powders, there is a possibility that the non-interacting powders agglomerate during drying, but in the case of interacting powders, this possibility is low. From this point of view, the interacting powder is preferably an acid-modified resin, more preferably a maleic anhydride-modified resin, and particularly preferably a maleic anhydride-modified polypropylene (MAPP). Details of the acid-modified resin will be described later.

Here, interacting means forming strong bonds with cellulose through covalent bonds, ionic bonds, and metallic bonds (that is, hydrogen bonds and van der Waals forces are not included in the concept of interacting). .). Preferably, a strong bond is a bond with a bond energy of 100 kJ/mol or more.

The volume average particle size of the interacting powder is preferably 0.01 to 10000 μm, more preferably 50 to 750 μm, particularly preferably 150 to 450 μm. If the volume average particle size exceeds 10,000 μm, the interacting powder may enter the gaps between the cellulose fibers and the effect of inhibiting aggregation may not be exhibited. On the other hand, when the volume average particle size is less than 0.01 μm, there is a possibility that hydrogen bonding between microfiber celluloses cannot be inhibited due to fineness.

The interacting powder preferably has a 90% particle size/10% particle size of 2-1000, more preferably 10-200. By setting the particle size ratio within this range, even when the fibrous cellulose is microfibrous cellulose and the fiber length varies, the effect of inhibiting the aggregation of interacting powders is fully exhibited. Specifically, when the 90% particle size/10% particle size ratio is less than 2, the particle sizes are too uniform, and it may be difficult to exhibit the effect of interaction only with fibers having a specific fiber length. On the other hand, if the ratio of 90% particle size/10% particle size is more than 1000, the variation in particle size becomes extremely large, possibly limiting the length of interacting fibers.

In the above, the 90% particle size means the particle size when the particle size is measured in order from the smallest particle size and the measured ratio is 90%. Moreover, the 10% particle size means the particle size when the measured ratio is 10% when the particle size is measured in ascending order.

The arithmetic standard deviation of the interacting powders is preferably 0.01-10000 μm, more preferably 1-5000 μm, particularly preferably 10-1000 μm. Even though the particle size of the powder varies as described above, there is a range of fibrous cellulose in the sense that the fibrous cellulose is microfibrous cellulose, thus specifying the arithmetic standard deviation of the powder. . In this regard, when the arithmetic standard deviation is less than 0.01 μm, the particle diameter becomes uniform, and it may be difficult to exhibit the effect of interaction only with fibers having a specific fiber length. On the other hand, if the arithmetic standard deviation exceeds 10,000 μm, the particle size becomes excessively non-uniform, the range of fiber lengths that can interact with each other widens, and it may be difficult to exhibit the effect of interaction.

Arithmetic standard deviation is a value measured by a particle size distribution analyzer (for example, a laser diffraction/scattering particle size distribution analyzer manufactured by Horiba, Ltd.).

The volume average particle diameter (μm) of interacting powder/average fiber length (μm) of fibrous cellulose is preferably 0.005 to 5000, more preferably 0.01 to 1000. Within this range, the powder and the fibers are more entangled, and aggregation of the fibers is suppressed. More specifically, when the volume average particle diameter of the interacting powder/average fiber length of the fibrous cellulose is less than 0.005, the fibers interact with each other and the interaction with the interacting powder is sufficient. However, the reinforcing effect may be insufficient. On the other hand, when the volume average particle diameter of the interacting powder/average fiber length of the fibrous cellulose exceeds 5000, the number of points that can interact with the interacting powder having a spherical shape becomes too small. There is a possibility that the reinforcing effect will be insufficient due to lack of interaction.

In this specification, the volume average particle size of the interacting powder is measured as it is or in the form of an aqueous dispersion using a particle size distribution analyzer (for example, a laser diffraction/scattering particle size distribution analyzer manufactured by Horiba, Ltd.). It is the volume average particle diameter calculated from the volume-based particle size distribution.

The interacting powder in this embodiment is preferably a resin powder. If the interacting powder is a resin powder, it melts during kneading and ceases to be grains, so the mixture of particles with different particle diameters has no effect at all. As the resin powder, for example, the same resin as used for obtaining the composite resin can be used. Of course, they may be of different types.

The content of the interacting powder is preferably 1 to 9,900% by mass, more preferably 5 to 1,900% by mass, particularly preferably 10 to 900% by mass, based on fibrous cellulose. If the blending amount is less than 1% by mass, it may enter the interstices of the cellulose fibers and the effect of suppressing aggregation may not be sufficiently exhibited. On the other hand, if the blending amount exceeds 9,900% by mass, there is a possibility that the function as cellulose fibers cannot be exhibited.

Inorganic powders can be used in addition to the interacting powders. When the interacting powder and the inorganic powder are used together, even when the inorganic powders and the interacting powders are mixed under the condition of agglomeration, the inorganic powder and the interacting powder are effectively prevented from cohesion. In addition, powder with a small particle size has a large surface area and is more susceptible to intermolecular forces than to gravity, and as a result, it tends to agglomerate. may not be loosened well in the slurry, or the powders may aggregate when the aqueous medium is removed, resulting in an insufficient effect of preventing the aggregation of the microfiber cellulose. However, it is believed that a combination of inorganic powders and interacting powders can mitigate self-agglomeration.

Examples of inorganic powders include simple substances and oxides of metal elements in Groups I to VIII of the periodic table, such as Fe, Na, K, Cu, Mg, Ca, Zn, Ba, Al, Ti, and silicon elements. , hydroxides, carbonates, sulfates, silicates, sulfites, and various clay minerals composed of these compounds. Specifically, for example, barium sulfate, calcium sulfate, magnesium sulfate, sodium sulfate, calcium sulfite, zinc oxide, ground calcium carbonate, ground calcium carbonate, aluminum borate, alumina, iron oxide, calcium titanate, aluminum hydroxide, Magnesium hydroxide, calcium hydroxide, sodium hydroxide, magnesium carbonate, calcium silicate, clay, wollastonite, glass beads, glass powder, silica gel, fumed silica, colloidal silica, silica sand, silica, quartz powder, diatomaceous earth, white carbon , glass fiber, and the like. A plurality of these inorganic powders may be contained. Further, it may be contained in waste paper pulp, or may be a so-called recycled filler obtained by recycling inorganic substances in papermaking sludge.

However, at least one inorganic powder selected from calcium carbonate, talc, white carbon, clay, calcined clay, titanium dioxide, aluminum hydroxide, recycled fillers, etc., which are suitably used as fillers and pigments for papermaking. is preferably used, more preferably at least one selected from calcium carbonate, talc and clay, and at least one of light calcium carbonate and heavy calcium carbonate is used Especially preferred. The use of calcium carbonate, talc, and clay facilitates formation of a composite with a matrix such as a resin. In addition, since it is a general-purpose inorganic material, there is an advantage that there are few restrictions on its use. Furthermore, calcium carbonate is particularly preferred for the following reasons. When using light calcium carbonate, it becomes easier to control the size and shape of the powder to be constant. Therefore, according to the size and shape of the cellulose fibers, the size and shape can be adjusted so that the effect of entering the gaps and suppressing the aggregation of the cellulose fibers can be easily generated, and the effect can be easily exerted with pinpoint accuracy. There is In addition, when heavy calcium carbonate is used, even if fibers of various sizes are present in the slurry, it will enter the gaps during the process of flocculating the fibers when the aqueous medium is removed, because the heavy calcium carbonate is amorphous. There is an advantage that it is possible to suppress aggregation of cellulose fibers with each other.

When the inorganic powder and the interacting powder are used together, the ratio of the average particle size of the inorganic powder to the average particle size of the interacting powder is preferably 1:0.1 to 1:10000, and 1:1 to 1:1000. is more preferred. Within this range, problems arising from the strength of its own cohesive force (for example, when mixing the powder and the microfiber cellulose slurry, the powder does not loosen well in the slurry, and when the aqueous medium is removed, the powder It is considered that the effect of preventing the aggregation of the microfiber cellulose can be fully exhibited without the problem of aggregation of the microfibers.

When inorganic powder and interacting powder are used in combination, the ratio of mass% of inorganic powder: mass% of interacting powder is preferably 1:0.01 to 1:100, and 1:0.1 to 1:10. is more preferred. It is considered that within this range, different types of powder can inhibit their own aggregation. Within this range, problems arising from the strength of its own cohesive force (for example, when mixing the powder and the microfiber cellulose slurry, the powder does not loosen well in the slurry, and when the aqueous medium is removed, the powder It is considered that the effect of preventing the aggregation of the microfiber cellulose can be fully exhibited without the problem of aggregation of the microfibers.

(Acid-modified resin)
As previously mentioned, the interacting powder is preferably a resin powder. Also, the resin is preferably an acid-modified resin. Acid-modified resins can ionically bond acid groups to some or all of the carbamate groups. Due to this ionic bond, the function of suppressing aggregation of the resin powder is effectively exhibited.

Examples of acid-modified resins that can be used include acid-modified polyolefin resins, acid-modified epoxy resins, acid-modified styrene elastomer resins, and the like. However, it is preferable to use an acid-modified polyolefin resin. An acid-modified polyolefin resin is a copolymer of an unsaturated carboxylic acid component and a polyolefin component.

As the polyolefin component, for example, one or more of alkene polymers such as ethylene, propylene, butadiene and isoprene can be selected and used. However, it is preferable to use polypropylene resin, which is a polymer of propylene.

As the unsaturated carboxylic acid component, for example, one or more selected from maleic anhydrides, phthalic anhydrides, itaconic anhydrides, citraconic anhydrides, citric anhydrides and the like can be used. Preferably, however, maleic anhydrides are used. In other words, it is particularly preferable to use a maleic anhydride-modified polypropylene resin.

The amount of the acid-modified resin to be mixed is preferably 0.1 to 1,000 parts by mass, more preferably 1 to 500 parts by mass, and particularly preferably 10 to 200 parts by mass with respect to 100 parts by mass of the microfiber cellulose. Particularly when the acid-modified resin is a maleic anhydride-modified polypropylene resin, the amount is preferably 1 to 200 parts by mass, more preferably 10 to 100 parts by mass. If the mixed amount of the acid-modified resin is less than 0.1 parts by mass, the anti-agglomeration effect is not sufficient. On the other hand, if the mixing amount exceeds 1,000 parts by mass, the anti-agglomeration effect tends to decrease.

The weight average molecular weight of maleic anhydride-modified polypropylene is, for example, 1,000 to 100,000, preferably 3,000 to 50,000.

Moreover, the acid value of the maleic anhydride-modified polypropylene is preferably 0.5 mgKOH/g or more and 100 mgKOH/g or less, and more preferably 1 mgKOH/g or more and 50 mgKOH/g or less.

The acid value of the maleic anhydride-modified polypropylene is a value determined by titration with potassium hydroxide according to JIS-K2501.

(dispersant)
Microfibrous cellulose is more desirable when mixed with a dispersant. As the dispersing agent, a compound having an aromatic compound having an amine group and/or a hydroxyl group and an aliphatic compound having an amine group and/or a hydroxyl group are preferable.

Examples of compounds having an amine group and/or hydroxyl group in aromatics include anilines, toluidines, trimethylanilines, anisidines, tyramines, histamines, tryptamines, phenols, dibutylhydroxytoluenes, bisphenol A cresols, eugenols, gallic acids, guaiacols, picric acids, phenolphthaleins, serotonins, dopamines, adrenaline, noradrenaline, thymols, tyrosines, salicylic acids, methyl salicylates, anise alcohols , salicyl alcohols, sinapyl alcohols, diphenidols, diphenylmethanols, cinnamyl alcohols, scopolamines, tryptophors, vanillyl alcohols, 3-phenyl-1-propanols, phenethyl alcohols, phenoxyethanols , veratryl alcohols, benzyl alcohols, benzoins, mandelic acids, mandelonitriles, benzoic acids, phthalic acids, isophthalic acids, terephthalic acids, mellitic acids, and cinnamic acids.

Examples of compounds having an amine group and/or a hydroxyl group in an aliphatic group include capryl alcohols, 2-ethylhexanols, pelargon alcohols, capric alcohols, undecyl alcohols, lauryl alcohols, and tridecyl alcohols. , myristyl alcohols, pentadecyl alcohols, cetanols, stearyl alcohols, elaidyl alcohols, oleyl alcohols, linoleyl alcohols, methylamines, dimethylamines, trimethylamines, ethylamines, diethylamines, ethylenediamine triethanolamines, N,N-diisopropylethylamines, tetramethylethylenediamines, hexamethylenediamines, spermidines, spermines, amantadine, formic acids, acetic acids, propionic acids, butyric acids, valeric acids, Caproic acids, enanthic acids, caprylic acids, pelargonic acids, capric acids, lauric acids, myristic acids, palmitic acids, margaric acids, stearic acids, oleic acids, linoleic acids, linolenic acids, arachidonic acids, eicosapentaenoic acids, docosahexaenoic acids, sorbin acids and the like.

The above dispersants inhibit hydrogen bonding between cellulose fibers. Therefore, the microfiber cellulose is reliably dispersed in the resin when the microfiber cellulose and the resin are kneaded. The above dispersants also play a role in improving the compatibility of the microfiber cellulose and the resin. In this respect, the dispersibility of the microfiber cellulose in the resin is improved.

It is conceivable to add a compatibilizer (drug) separately when kneading the fibrous cellulose and the resin, but rather than adding the drug at this stage, the fibrous cellulose and the dispersant (drug) are mixed in advance. In this case, the drug is evenly attached to the fibrous cellulose, and the effect of improving the compatibility with the resin is enhanced.

Further, for example, polypropylene has a melting point of 160°C, and therefore fibrous cellulose and resin are kneaded at about 180°C. However, if the dispersing agent (liquid) is added in this state, it dries up in an instant. Therefore, there is a method of using a resin with a low melting point to prepare a masterbatch (composite resin with a high concentration of microfiber cellulose), and then reducing the concentration with a normal resin. However, resins with low melting points generally have low strength. Therefore, according to this method, the strength of the composite resin may decrease.

The amount of the dispersant mixed is preferably 0.1 to 1,000 parts by weight, more preferably 1 to 500 parts by weight, and particularly preferably 10 to 200 parts by weight, based on 100 parts by weight of the microfiber cellulose. If the amount of the dispersant mixed is less than 0.1 part by mass, there is a possibility that the improvement in resin strength will be insufficient. On the other hand, if the mixing amount exceeds 1,000 parts by mass, it becomes excessive and the resin strength tends to decrease.

In this regard, the above-mentioned acid-modified resin is intended to improve compatibility by forming an ionic bond between the acid group and the carbamate group of the microfiber cellulose, thereby enhancing the reinforcing effect. (Improved adhesion) and strength. On the other hand, the above-mentioned dispersant intervenes between the hydroxyl groups of the microfiber cellulose to prevent aggregation, thereby improving the dispersibility in the resin. , it can enter the narrow spaces between microfiber cellulose where the acid-modified resin cannot enter, and plays a role of improving dispersibility and strength. From the above viewpoints, the molecular weight of the acid-modified resin is preferably 2 to 2,000 times, preferably 5 to 1,000 times the molecular weight of the dispersant.

To explain the above in more detail, the interacting powder physically intervenes between the microfiber celluloses to inhibit hydrogen bonding, thereby improving the dispersibility of the microfiber cellulose. In particular, the acid-modified resin ionically bonds the acid groups with the carbamate groups of the microfiber cellulose. Therefore, it comes to be present around the fibers preferentially over other substances, and the effect of suppressing aggregation of the fibers is exhibited. Moreover, when the fibrous cellulose-containing material and the resin are mixed to form a composite resin, it plays a role of adhering the composite resin and the microfiber cellulose, thereby improving the mechanical strength of the composite resin. In this respect, the dispersing agent inhibits hydrogen bonding between microfiber celluloses, but since the interacting powder is micro-order, it physically intervenes to suppress hydrogen bonding. Therefore, although the dispersibility is lower than that of a dispersant, especially in the case of a resin powder, it melts and becomes a matrix, so it does not contribute to deterioration of physical properties. On the other hand, since the dispersant is at the molecular level and is extremely small, it is highly effective in inhibiting hydrogen bonding by covering the cellulose microfibers and improving the dispersibility of the cellulose microfibers. However, it may remain in the resin and work to deteriorate physical properties.

(Manufacturing method of composite resin)
Mixtures such as fibrous cellulose inclusions and dispersants can be dried and ground into a powder prior to kneading with the resin. According to this form, it is not necessary to dry the fibrous cellulose when kneading with the resin, and the heat efficiency is good. In addition, when the mixture contains an interacting powder or dispersant, even if the mixture is dried, there is a low possibility that the fibrous cellulose (microfiber cellulose) will not be redispersed.

The mixture is optionally dewatered to dehydrate prior to drying. For this dehydration, for example, one or more types are selected from dehydration devices such as belt presses, screw presses, filter presses, twin rolls, twin wire formers, valveless filters, center disk filters, membrane processing, and centrifugal separators. can be done using

Drying of the mixture includes, for example, rotary kiln drying, disk drying, air stream drying, medium fluidized drying, spray drying, drum drying, screw conveyor drying, paddle drying, uniaxial kneading drying, multi-screw kneading drying, vacuum drying, and stirring drying. It can be carried out by selecting and using one or more of these.

The dry mixture (dry matter) is ground to a powder. Pulverization of the dried product can be carried out by selecting and using one or more of, for example, bead mills, kneaders, dispersers, twist mills, cut mills, hammer mills, and the like.

The average particle size of the powder is preferably 1-10,000 μm, more preferably 10-5,000 μm, particularly preferably 100-1,000 μm. If the average particle size of the powder exceeds 10,000 μm, the kneadability with the resin may be poor. On the other hand, it is not economical because a large amount of energy is required to reduce the average particle size of the powder to less than 1 μm.

The average particle size of the powder can be controlled not only by controlling the degree of pulverization, but also by classification using a classifier such as a filter or cyclone.

The bulk specific gravity of the mixture (powder) is preferably 0.03 to 1.0, more preferably 0.04 to 0.9, and particularly preferably 0.05 to 0.8. A bulk specific gravity of more than 1.0 means that the hydrogen bonding between fibrous celluloses is stronger and it is not easy to disperse the fibrous cellulose in the resin. On the other hand, setting the bulk specific gravity below 0.03 is disadvantageous in terms of transportation costs.

Bulk specific gravity is a value measured according to JIS K7365.

The moisture content of the mixture (powder) is preferably 50% or less, more preferably 30% or less, and particularly preferably 10% or less. If the moisture content exceeds 50%, the energy required for kneading with the resin is enormous, which is not economical. The moisture content is a value calculated by the following formula, using a constant temperature drier, holding the sample at 105° C. for 6 hours or more, and using the mass after drying as the mass when no change in mass is observed.
Fiber moisture content (%) = [(mass before drying - mass after drying) / mass before drying] x 100

The powdery material (fibrous cellulose-containing material) obtained as described above is kneaded with a resin, if necessary, to obtain a fibrous cellulose composite resin. This kneading can be carried out, for example, by mixing a pellet-shaped resin and a powdery material, or by first melting the resin and then adding the powdery material to the melt. When resin powder such as acid-modified resin is used as the interacting powder, it can be kneaded immediately without being mixed with the resin to form a composite resin.

The mixture (powder, fibrous cellulose-containing material) preferably contains more than 55 parts by mass of fibrous cellulose, particularly 60 parts by mass or more, when the total amount is 100 parts by mass. Normally, when a mixture having a fibrous cellulose concentration exceeding 55 parts by mass is kneaded with a resin, the dispersibility of the mixture in the resin deteriorates, resulting in poor mixability. On the other hand, the mixture of the present invention contains fibrous cellulose in which some or all of the hydroxyl groups are substituted with carbamate groups, and powder that interacts with the fibrous cellulose, so that the fibrous cellulose is 55 Even if it exceeds parts by mass, high dispersibility can be maintained when the mixture is kneaded with the resin. Increasing the concentration of fibrous cellulose in the mixture is also preferable from the viewpoint that the amount of the mixture used to contain a desired proportion of fibrous cellulose in the composite resin can be reduced.

For the kneading treatment, for example, one or more selected from single-screw or multi-screw kneaders with two or more screws, mixing rolls, kneaders, roll mills, Banbury mixers, screw presses, dispersers, etc. are used. be able to. Among them, it is preferable to use a multi-screw kneader with two or more screws. Two or more multi-screw kneaders with two or more screws may be used in parallel or in series.

The temperature of the kneading treatment is higher than the glass transition point of the resin, and varies depending on the type of resin, but is preferably 80 to 280°C, more preferably 90 to 260°C, and more preferably 100 to 240°C. is particularly preferred.

At least one of a thermoplastic resin and a thermosetting resin can be used as the resin.

Examples of thermoplastic resins include polyolefins such as polypropylene (PP) and polyethylene (PE), polyester resins such as aliphatic polyester resins and aromatic polyester resins, polyacrylic resins such as polystyrene, methacrylates and acrylates, polyamide resins, One or more of polycarbonate resins, polyacetal resins and the like can be selected and used.

However, it is preferable to use at least one of polyolefin and polyester resin. Polypropylene is preferably used as the polyolefin. Furthermore, as polyester resins, aliphatic polyester resins such as polylactic acid and polycaprolactone can be exemplified, and aromatic polyester resins such as polyethylene terephthalate can be exemplified. It is preferable to use a polyester resin having

As the biodegradable resin, for example, one or more of hydroxycarboxylic acid-based aliphatic polyesters, caprolactone-based aliphatic polyesters, dibasic acid polyesters, and the like can be selected and used.

Hydroxycarboxylic acid-based aliphatic polyesters include, for example, homopolymers of hydroxycarboxylic acids such as lactic acid, malic acid, glucose acid, and 3-hydroxybutyric acid, and copolymers using at least one of these hydroxycarboxylic acids. One or two or more may be selected and used from among polymers and the like. However, it is preferable to use polylactic acid, a copolymer of lactic acid and the above hydroxycarboxylic acids other than lactic acid, polycaprolactone, and a copolymer of at least one of the above hydroxycarboxylic acids and caprolactone. It is particularly preferred to use

As the lactic acid, for example, L-lactic acid, D-lactic acid, or the like can be used, and these lactic acids may be used alone or two or more of them may be selected and used.

As the caprolactone-based aliphatic polyester, for example, one or more of polycaprolactone homopolymers and copolymers of polycaprolactone and the above hydroxycarboxylic acids can be selected and used. .

As the dibasic acid polyester, for example, one or more of polybutylene succinate, polyethylene succinate, polybutylene adipate and the like can be selected and used.

A biodegradable resin may be used individually by 1 type, or may use 2 or more types together.

Examples of thermosetting resins include phenol resins, urea resins, melamine resins, furan resins, unsaturated polyesters, diallyl phthalate resins, vinyl ester resins, epoxy resins, urethane resins, silicone resins, thermosetting polyimide resins, and the like. can be used. These resins can be used alone or in combination of two or more.

The blending ratio of fibrous cellulose and resin is preferably 1 part by mass or more of fibrous cellulose and 99 parts by mass or less of resin, more preferably 2 parts by mass or more of fibrous cellulose and 98 parts by mass or less of resin, and particularly preferably The fibrous cellulose is 3 parts by mass or more, and the resin is 97 parts by mass or less. Also, preferably 50 parts by mass or less of fibrous cellulose, 50 parts by mass or more of resin, more preferably 40 parts by mass or less of fibrous cellulose, 60 parts by mass or more of resin, and particularly preferably 30 parts by mass or less of fibrous cellulose. , resin is 70 parts by mass or more. In particular, when the fibrous cellulose is 10 to 50 parts by mass, the strength of the resin composition, particularly the bending strength and tensile modulus strength, can be remarkably improved.

In addition, the content ratio of the fibrous cellulose and the resin contained in the finally obtained resin composition is usually the same as the above mixing ratio of the fibrous cellulose and the resin.

If the difference in the solubility parameter (cal/cm ³ ) ^1/2 (SP value) of microfiber cellulose and resin, that is, the SP _MFC value of microfiber cellulose and the SP _POL value of resin, the difference in SP value = SP _MFC value -SP can be a _POL value. The SP value difference is preferably 10 to 0.1, more preferably 8 to 0.5, and particularly preferably 5 to 1. If the SP value difference exceeds 10, the microfiber cellulose will not be dispersed in the resin, and the reinforcing effect cannot be obtained. On the other hand, if the difference in SP value is less than 0.1, the microfiber cellulose will dissolve in the resin and will not function as a filler, failing to obtain a reinforcing effect. In this regard, the smaller the difference between the SP _POL value of the resin (solvent) and the SP _MFC value of the microfiber cellulose (solute), the greater the reinforcing effect.

The solubility parameter (cal/cm ³ ) ^1/2 (SP value) is a measure of the intermolecular force acting between a solvent and a solute. Solvents and solutes with closer SP values have higher solubility. .

(Molding process)
The kneaded product of fibrous cellulose-containing material and resin can be molded into a desired shape after kneading again if necessary. The size, thickness, shape, and the like of this molding are not particularly limited, and may be, for example, sheet-like, pellet-like, powder-like, fibrous-like, or the like.

The temperature during the molding process is equal to or higher than the glass transition point of the resin, and is, for example, 90 to 260°C, preferably 100 to 240°C, depending on the type of resin.

The kneaded product can be molded by, for example, mold molding, injection molding, extrusion molding, blow molding, foam molding, and the like. Alternatively, the kneaded product may be spun into a fibrous form and mixed with the above-described plant material or the like to form a mat or board. Mixing can be carried out by, for example, a method of simultaneous deposition by air laying.

As a device for molding the kneaded material, for example, one or two of injection molding machines, blow molding machines, blow molding machines, blow molding machines, compression molding machines, extrusion molding machines, vacuum molding machines, air pressure molding machines, etc. More than one species can be selected and used.

The above molding may be carried out after kneading, or the kneaded product may be cooled once, chipped using a crusher or the like, and then the chips may be put into a molding machine such as an extruder or an injection molding machine. can also be done. Of course, molding is not an essential requirement of the invention.

(Other compositions)
The fibrous cellulose inclusions may include cellulose nanofibers along with microfibrous cellulose. Cellulose nanofibers are fine fibers like microfiber cellulose, and have a role to complement microfiber cellulose for improving the strength of resin. However, if possible, it is preferable to use only microfiber cellulose without including cellulose nanofibers as fine fibers. The average fiber diameter (average fiber width, average diameter of single fibers) of cellulose nanofibers is preferably 4 to 100 nm, more preferably 10 to 80 nm.

The fibrous cellulose-containing material may also contain pulp. Pulp has the role of greatly improving the dewaterability of the cellulose fiber slurry. However, as in the case of cellulose nanofibers, it is most preferable not to mix pulp, that is, the content is 0% by mass.

In addition to fine fibers and pulp, resin compositions (composite resins) include kenaf, jute hemp, manila hemp, sisal hemp, ganpi, mitsumata, kozo, bananas, pineapples, coconut palms, corn, sugar cane, bagasse, coconut palms, papyrus, Fibers derived from plant materials obtained from various plants such as reeds, esparto, surviving grass, wheat, rice, bamboo, various conifers (such as cedar and cypress), broad-leaved trees, and cotton can be included, and are included. good too.

For the resin composition, for example, one or more selected from among antistatic agents, flame retardants, antibacterial agents, colorants, radical scavengers, foaming agents, etc., within a range that does not impede the effects of the present invention. can be added at These raw materials may be added to the fibrous cellulose dispersion, added during kneading of the fibrous cellulose and resin, added to the kneaded product, or added by other methods. good. However, from the viewpoint of production efficiency, it is preferable to add the fibrous cellulose and the resin during kneading.

The resin composition may contain an ethylene-α-olefin copolymer elastomer or a styrene-butadiene block copolymer as a rubber component. Examples of α-olefins include, for example, butene, isobutene, pentene, hexene, methyl-pentene, octene, decene, dodecene, and the like.

Next, examples of the present invention will be described.
Maleic anhydride-modified polypropylene (MAPP) with a uniform particle size or maleic anhydride-modified polypropylene (MAPP) with a mixture of different particle sizes was added to 1,570 g of microfiber cellulose with a solid content concentration of 2.8% by mass. 22.0 g was added and heated using a contact dryer heated to 140° C. to obtain a carbamate-modified microfiber cellulose inclusion. The moisture content of the carbamate-modified microfibrous cellulose inclusions was 5-22%.

The method for carbamate modification of the fiber was as follows.
That is, using softwood kraft pulp with a moisture content of 10% or less, an aqueous urea solution with a solid concentration of 10%, and an aqueous 20% citric acid solution, the mass ratio of pulp: urea: citric acid = 100: 50: 0 in terms of solid content. After mixing to .1, it was dried at 105°C. Next, heat treatment was performed at a predetermined reaction temperature and reaction time to obtain carbamate-modified pulp (carbamate-modified pulp). The resulting carbamate-modified pulp was diluted with distilled water and stirred, and the dehydration step was repeated twice. The washed carbamate-modified pulp is beaten using a beater until the ratio of less than 0.2 mm and the ratio of 0.2 to 0.6 mm reach a predetermined ratio, and carbamate-modified microfiber cellulose (carbamate MFC (fine fiber)) was obtained.

Also, 22.0 g of polypropylene powder was used in place of the maleic anhydride-modified polypropylene to obtain a carbamate-modified microfiber cellulose-containing material as a comparative example. The moisture content of the carbamate-modified microfibrous cellulose inclusions was 5-22%.

Polypropylene pellets were added to the carbamate-modified microfiber cellulose-containing material obtained as described above, and the ratio of carbamate-modified microfiber: other components = 10:90. to obtain a carbamate-modified microfiber cellulose composite resin with a fiber content of 10%.

The carbamate-modified microfiber cellulose composite resin obtained as described above was cut into cylinders with a diameter of 2 mm and a length of 2 mm with a pelleter, and a rectangular parallelepiped test piece (length 59 mm, width 9.6 mm, thickness 3.8 mm) was obtained at 180 ° C. ). The flexural modulus was examined for each specimen. The results are shown in Table 1 together with the particle size (particle diameter) of MAPP and the fiber size (fiber length) of fibrous cellulose according to the following criteria.

(flexural modulus)
The flexural modulus was measured according to JIS K7171:2008. In the table, the evaluation results are shown according to the following criteria.
When the bending elastic modulus of the resin itself is 1 and the bending elastic modulus (magnification) of the composite resin is 1.45 times or more: ○
When the bending elastic modulus of the resin itself is 1 and the bending elastic modulus (magnification) of the composite resin is 1.40 times or more and less than 1.45 times: △

If the bending elastic modulus (magnification) of the composite resin is less than 1.40 times assuming that the bending elastic modulus of the resin itself is 1: ×

INDUSTRIAL APPLICABILITY The present invention can be used as a fibrous cellulose-containing material, a fibrous cellulose composite resin, and a method for producing a fibrous cellulose-containing material. For example, fibrous cellulose composite resins are used for interior materials, exterior materials, structural materials, etc. of transportation equipment such as automobiles, trains, ships, and airplanes; Parts, etc.; Housings, structural materials, internal parts, etc. of mobile communication devices such as mobile phones; Structural materials, internal parts, etc.; interior materials, exterior materials, structural materials, etc. for buildings and furniture; office equipment, etc. such as stationery; Available.

Claims (9)

A fibrous cellulose inclusion added to the resin,
The fibrous cellulose has an average fiber width of 0.1 to 19 μm, and some or all of the hydroxyl groups are substituted with carbamate groups,
comprising a powder that interacts with the fibrous cellulose;
A fibrous cellulose-containing material characterized by: The interacting powder has a 90% particle size/10% particle size of 2 to 1000.
The fibrous cellulose inclusion according to claim 1. The volume average particle diameter of the interacting powder is 0.01 to 10000 μm, and the volume average particle diameter (μm) of the interacting powder/average fiber length (μm) of the fibrous cellulose is 0.005 to 5000. is
The fibrous cellulose containing material according to claim 1 or claim 2. The fibrous cellulose has a fiber length of less than 0.2 mm in a proportion of 5% or more and a fiber length of 0.2 to 0.6 mm in a proportion of 10% or more.
The fibrous cellulose-containing material according to any one of claims 1-3. The fibrous cellulose has an average fiber length of 1.0 mm or less, an average fiber width of 10 μm or less, and a fibrillation rate of 2.5% or more.
The fibrous cellulose-containing material according to any one of claims 1-4. The interacting powder is an acid-modified resin having an acid value of 2.0% or more,
The fibrous cellulose-containing material according to any one of claims 1-5. wherein said interacting powder is maleic anhydride modified polypropylene;
The fibrous cellulose-containing material according to any one of claims 1-6. A fibrous cellulose composite resin in which fibrous cellulose and resin are mixed,
The fibrous cellulose-containing material according to any one of claims 1 to 7 is used as the fibrous cellulose,
A fibrous cellulose composite resin characterized by: Fibrous cellulose in which some or all of the hydroxyl groups have been substituted with carbamate groups is defibrated so that the average fiber width is 0.1 to 19 μm, and mixed with the powder that interacts with the fibrous cellulose to obtain a mixed solution. get
drying the mixture,
A method for producing a fibrous cellulose-containing material, characterized by: